You might think that a red flag within the last 10 laps of the Monaco GP would be a recipe for an exciting conclusion, by closing up the whole field and allowing for a spectacular sprint to the flag at the resumption.
However, in 2011 it had the opposite effect. We already had a finely-balanced thriller, with Sebastian Vettel, Fernando Alonso and Jenson Button running nose-to-tail.
Having run one, two and three stop strategies respectively they had ended up on the same place of track at the same time, but with tyres of widely varying age and performance. As a result there was a good chance of some last minute overtaking.
And then the red flag robbed fans of a thrilling finish to the race by allowing everyone to change tyres for the restart. It gave Vettel, who had endured a disastrous Red Bull pitstop and was pushing his tyres to the very limit, a get-out-of-jail free card.
A red flag stoppage had also turned qualifying on its head, generating a grid made up of times set on the first runs, and leaving Button's McLaren teammate Lewis Hamilton stranded down the field in ninth.
Vettel: The perfect start
Pole is normally a pretty secure place to start at Monaco, and Vettel felt a little more comfortable about having Button right behind.
Sebastian Vettel, Red Bull RB7 Renault leads at the start
Rainer W. Schlegelmilch
Vettel duly held onto his advantage, and with no immediate pressure in his mirrors, the German was able to find a good rhythm, putting in quick times while protecting his supersofts as best as he could.
The gap grew to 4.3s by lap 4, and it looked like we might in for a demonstration run. But then it stabilised. Vettel lost a bit of time passing backmarkers, and perhaps spurred by that handy gain, Button dived into the pits to take on supersofts, the deficit to Vettel having now been cut to less than 3s.
Given that Red Bull was bound to respond, there still was no way Button was going to jump ahead, and neither Vettel nor his crew should have been under any undue pressure for what should have been a very routine covering operation.
Red Bull gets it wrong
But that's where it all went wrong. For reasons the team couldn't explain in the immediate aftermath, the request to fit supersoft tyres, to shadow what Button was doing, didn't get through to the pit crew.
Communications are more complicated at Monaco than anywhere else for the simple reason that the engineers on the pit stand are in the building above the garage rather than on the pit wall as at every race, from where they can simply turn round and see what's happening.
That didn't help in this situation, and McLaren had an even more costly faux pas with Hamilton later in the race, when no tyres were ready when he came in.
"We had an issue at the first stop where the radio seemed to get jammed," said Christian Horner. "And the communication from the pitwall guys upstairs didn't reach the guys downstairs, so there was some confusion.
"We were looking at going on another set of options and he drove out of the pitlane with another set of primes on that went to the car late, so not only did he lose time, we didn't get the tyre of choice."
In the confusion the stop had dragged out. He spent 3.2s longer in the pitlane than Button had. When he emerged Button had blasted past, having also banged in a superb out lap on his fresh ex-qualifying supersofts.
On lap 14 Vettel had been 3.7s ahead of Button. By the time he completed lap 17, the first out of the pits on the less favourable softs, he was 4.1s behind. A remarkable turnaround, and a massive headache for Red Bull.
Sebastian Vettel, Red Bull RB7 Renault
Rainer W. Schlegelmilch
It wasn't even a case of switching to Plan B or C, this was something totally unexpected, and which set the team strategists scrambling. The only positive was that having used both tyres Vettel could – in theory – now get to the finish without another stop.
Initially it looked like an impossible ask, given that the tyres would have to do 62 laps, way, way more than anyone in the paddock had anticipated. The only real hope was that if some safety car interludes calmed things down, there was a tiny chance that he could do it.
The long way home for Vettel
Vettel couldn't allow Button to get far enough ahead so that the McLaren could make a second stop and come out still in front.
If he did that and put on the softs, it would be game over – they would now be on the same tyres, both in a position to get to the end, but Jenson's would have been that much fresher.
For a while, it looked like Button might do it. By lap 26 the gap was as high as 14.9s. But then traffic began to trip him up, and with his supersofts past their best, he couldn't make any more progress. Crucially Vettel hung in there, keeping the margin at 13-14s.
This was a tricky one for McLaren, as Button had lost momentum. They team had to do something, choosing to bring him in on lap 33.
They knew he would come out still behind Vettel, but it was a question of either a) putting him onto softs and creating a potential race to the flag with Button on tyres that were 17 laps younger, or b) taking another set of supersofts and giving their man some pace and overtaking potential.
With the latter strategy Button would have to stop again for softs and he was relying pretty much on Vettel having to make another step, even though he didn't have to.
Sebastian Vettel, Red Bull RB7 Renault follows the safety car
Rainer W. Schlegelmilch
In the end McLaren went for Plan A. And no sooner had he made the stop than the safety car came out after Felipe Massa crashed his Ferrari in the tunnel.
This was a fascinating development. It was crunch time for Vettel – he could pit under the safety car, and drop back behind Button, or stay out and try to get the tyres to the end. There were still some 44 laps to run, and it looked like a daunting task, but he chose to roll the dice and stay out.
Button meanwhile was behind him the safety car queue, albeit with lapped cars in the way preventing him from being in a position to immediately attack Vettel at the restart.
By lap 41, just three laps after the green, Button was right on the Red Bull's tail. This was truly fascinating stuff. Button could push because he could use up those tyres.
Indeed he had to go for it, because he had to find a way to squeeze in a stop for soft tyres, and that meant getting past Vettel.
Vettel meanwhile just had to focus on the long game and somehow stay ahead while preserving his tyres.
"We believed that we had a quick race car here," said McLaren's Martin Whitmarsh. "But a quick race car without track position isn't good enough, so you had to get track position. So we were trying hard to get that, and trying hard to find a way through."
However, Button couldn't find a way by. Meanwhile McLaren's attention had by now been diverted to Alonso.
Ferrari had made a great call under the Massa safety car. Having watched Button take the supersofts on lap 34 the team put Alonso onto softs on the basis that a 44 lap run to the finish was feasible.
It was clear also that at least the first few laps would be run under safety car conditions, which would give the tyres a little extra respite. With Button stuck behind Vettel, Fernando was closing in.
Button had to stop and drop behind Alonso at some stage, and McLaren brought him in for softs on lap 48, after he'd run 15-18-15 laps on his three sets of supersofts.
Thus at the end of lap 49, Jenson's out lap on the new tyres, Vettel was 5.9s clear of Alonso, while Button was a further 14s behind the Ferrari.
Now it was simply a question of the maths, with everyone's tyres losing performance by the lap. Vettel's were 33 laps old, Alonso's had done 15, and Button's just the one.
Sebastian Vettel, Red Bull RB7 Renault, locks up
Rainer W. Schlegelmilch
Vettel knew that the others would catch him, and he really had to use his head. It was pointless to go flat out – he had to keep some life in the tyres and save some performance for when his rivals appeared in his mirrors.
Alonso was in striking distance by lap 57 and Jenson joined the party on lap 62. With 16 laps to go it was now all about survival for Vettel.
"We were trying it as we went along really!," Red Bull's Adrian Newey told me. "It was unexplored territory, put it that way. We knew that they would last a lot longer than the options, but we didn't know exactly how much longer. It worked, that's the main thing."
"Every lap Seb was making it go longer, and longer and longer," said Horner. "And he's saying the tyres are OK, I'm OK, I'm OK. He made the strategy work today. So in the end we decided OK, we'll roll the dice, worst case we're going to be third, and we'll try to make it work...
"It's a tough call, because you're heading into the unknown. China wasn't that long ago where he didn't quite get to the end. But it worked. It wasn't a situation that we wanted to find ourselves in, but we worked our way out of it, which was phenomenal."
It wasn't just luck. Under the most intense pressure Vettel gave his pursuers a masterclass in defensive driving.
"Alonso made it even more complicated, because that throws another dynamic in," said Horner. "You can cover one, but you can't cover both. In the end he was putting a huge amount of pressure on Seb. Seb was working very, very hard on the exit into the tunnel, onto the pit straight."
Alonso was saving himself for a late attack, and he later he said mischievously that he had a lot less to lose than Vettel, and he was willing to risk a crash.
Button was also being patient and had a feeling that his rivals would take care of each other. It was a great stuff.
Vettel gets a break
We'll never know what would have happened, for we were robbed of potentially the most exciting Monaco finish in years when the red flag came out, all three drivers having somehow slipped through the carnage as Hamilton, Jaime Alguersuari and Vitaly Petrov tangled at the Swimming Pool.
Vitaly Petrov, Lotus Renault GP R31 after the crash
The FIA tried to do the right thing. Believing he was hurt, Petrov stayed in the car and shouted "hospital, hospital," into his radio, which was a little alarming for the team.
Told by the medical crew at the scene that the extraction might take 20 minutes, race director Charlie Whiting suspended the race rather than let it run to the flag under a safety car, which he could easily have chosen to do. His reasoning was that everyone around the world deserved a chance to see a proper finish.
Unfortunately, we didn't get the denouement that we deserved. Under the race suspension rule at that time teams were allowed to work on their cars during the interval, and that meant they were also allowed to change tyres.
The way the FIA viewed it, it was as if the safety car was out but not moving, and in effect everyone was entitled to a free pitstop on the grid.
The fact that teams could fit new tyres came as a surprise to many observers, but there was some logic to it. There was a chance that cars had run over debris, and also interruptions might involve rain, and thus a change of tyres before the restart was a logical concession.
For the final six-lap sprint, Vettel and Alonso were able to fit used supersofts, while Button faced a double whammy. Not only did he lose the tyre advantage he had before the stoppage, he had no supersofts left, so had to take the slower softs, albeit a new set.
"I think we would have very strong from that position," said Whitmarsh, "because it would have been almost impossible for the others to put temperature back into very old worn tyres. So it was a bit frustrating."
After the restart, the last few laps were a formality for Vettel, and he simply drove around in front to take the flag.
"He drove an absolutely immaculate race," said Horner. "And he made it work, even without the restart he would have held on. It was a straightforward race to the finish, and on the options we were relatively comfortable."
"Seb did a great job of managing it," said Newey. "It was obviously a long run on a set of primes. Right at the end having the red flag meant a few less laps on those tyres. Looking at their condition he would probably have made it anyway."
But would he really have held on? The Red Bull guys may have been confident, but remember there was a long way to go. The Petrov accident happened during lap 69, so when the safety car first emerged, there were actually nine laps left, rather than the six we eventually had at the restart after the safety car interlude. Could Vettel really have survived those nine racing laps in front?
A marshal signals Mark Webber, Red Bull RB7 Renault, to slow down
Rainer W. Schlegelmilch
At that stage his tyres were already 53 laps old, and he was shooting for 62. He'd been given a little breathing space when the Massa safety car allowed him to give the tyres a rest, but nobody else came anywhere close to his target – when the safety car came out Alonso's had done 35.
The longest pitstop-to-pitstop stint anyone logged on the softs during the race was 39, by Vettel's teammate Mark Webber. Talk about a voyage into the unknown.
What might have been
Alonso put in a great performance, and the man himself was pretty confident that he could have found a way past Vettel, and kept Button behind.
Button's drive was overshadowed by the fuss about his teammate's wild Sunday afternoon. He had contact with Michael Schumacher, Massa, Alguersuari and Pastor Maldonado, experienced a disastrously long tyre stop, took a drive through for causing a collision, and needed a complete new rear wing before the restart – and yet he still finished sixth.
If all the aggression we saw had been channelled into the battle for the lead instead of the minor placings, perhaps we would really have had a race.
Sebastian Vettel, Red Bull RB7 Renault, celebrates
Rainer W. Schlegelmilch