Chelsea could afford to miss a late penalty in a 1-1 draw at Liverpool on Tuesday, as Antonio Conte's side extended its lead at the top of the Premier League and its rivals sabotaged their own title bids.
Fourth-place Liverpool started well at Anfield, only for Chelsea to take the lead through center half David Luiz's free kick in the first half.
Netherlands midfielder Georginio Wijnaldum equalized in the second half for Liverpool, which then had goalkeeper Simon Mignolet to thank for saving Chelsea striker Diego Costa's spot-kick.
The draw set the stage perfectly for Arsenal to keep the pressure up in the title race with a routine home win against a Watford side well out of form.
The opposite happened, with the visitors scoring early goals and holding on for a 2-1 win that severely dents Arsenal's hopes of catching the leaders. Arsenal is now nine points behind Chelsea and surely has no choice but to beat the leaders at Stamford Bridge on Saturday.
Worse still for Arsenal, it dropped to third place on goal difference behind bitter north London rival Tottenham, which drew 0-0 away to relegation struggler Sunderland.
CHELSEA 1, LIVERPOOL 1
Having dropped goalkeeper Simon Mignolet earlier this season, Liverpool manager Juergen Klopp watched him save Diego Costa's late penalty to earn his side a draw.
The result spared Klopp the ignominy of a fourth straight defeat for the first time since 1923, but that will feel anecdotal when Klopp looks at the current situation.
The bleak reality is that his side — having started the season so brightly when it was scoring goals galore — remains 10 points adrift in the title race and is out of both domestic cup competitions.
Against the run of play, Mignolet was caught unawares by an opportunistic free kick from Luiz.
Midfielder Georginio Wijnaldum equalized for Liverpool in the 57th before Mignolet tipped Costa's spot kick around the post in the 76th.
Costa's miss did little to dampen Antonio Conte's mood.
The Chelsea manager was punching the air at the final whistle. No wonder, given that his rivals are failing to mount a proper challenge.
ARSENAL 1, WATFORD 2
There was no late escape for Arsene Wenger's side this time.
Arsenal has ridden its luck this season, scraping a 2-1 home win against Burnley in the previous league game with a penalty seven minutes into injury time. Then there was the last-gasp 3-3 draw away to Bournemouth after trailing 3-0, or the 86th minute winner against West Bromwich Albion.
Those were teams Arsenal was supposed to beat comfortably.
So was Watford, especially given its poor recent form and the fact Arsenal entered the match full of confidence after a 5-0 away win at Southampton in the FA Cup last weekend.
But it all went wrong.
Early strikes from center half Younes Kaboul and striker Troy Deeney gave Watford a deserved 2-0 halftime lead before winger Alex Iwobi pulled a goal back for Arsenal after the break.
Substitute Lucas Perez hit the crossbar late on for Arsenal as Watford held on for its first victory in eight Premier League games.
SUNDERLAND 0, TOTTENHAM 0
Tottenham leapfrogged Arsenal to move into second place but missed the opportunity to put some pressure on league leader Chelsea.
On a frustrating night for Tottenham, forward Son Heung-min struck an effort just clear of the crossbar in the second half.
The result was somewhat better for Sunderland, which managed to move off the bottom. Hull is now last on goal difference.
BURNLEY 1, LEICESTER 0
Defending champion Leicester is just two points above the relegation zone after a third straight Premier League defeat.
Center forward Sam Vokes scored from close range in the 87th minute to secure Burnley's seventh successive win at Turf Moor in all competitions.
While Leicester is in freefall, Burnely is collecting valuable points to stave off the threat of relegation and rose to ninth.
SWANSEA 2, SOUTHAMPTON 1
Gylfi Sigurdsson underlined his importance to Swansea with another winner as the Welsh side moved two points away from the relegation zone.
Swansea led through center half Alfie Mawson's header shortly before the break, but Ireland striker Shane Long equalized in the 57th.
With 20 minutes left, Sigurdsson sealed victory for the second straight game after netting the winner in a 3-2 win away to Liverpool 10 days ago.
Swansea, which is in 17th place, has a good chance to staying up if Sigurdsson keeps finding the net. The Iceland midfielder scored 11 league goals last season and already has seven.
BOURNEMOUTH 0, CRYSTAL PALACE 2
Sam Allardyce got his first Premier League win since taking charge of Crystal Palace.
Center back Scott Dann, now in his fourth season with Palace, has scored his share of goals and he put the visitors ahead from close range just after the break.
In injury time, Belgium forward Christian Benteke headed home his ninth league goal of the season.
Palace is in 18th place, two points behind Swansea, Leicester and Middlesbrough.
MIDDLESBROUGH 1, WEST BROMWICH ALBION 1
West Brom went ahead when former Middlesbrough midfielder James Morrison lashed home from 20 yards in the sixth minute.
Spanish striker Alvaro Negredo equalized from the penalty spot in the 17th.
Middlesbrough is in 15th place, while West Brom is eighth.