* Reed tames difficult conditions in New Jersey
* Shoots four-under-par 67 at Liberty National
* Halfway leader Johnson backtracks with a 74 (Adds quotes, details)
Aug 10 (Reuters) - Patrick Reed, without a win since his major breakthrough at last year's Masters, tamed demanding conditions to earn a one-shot lead over Abraham Ancer after the third round at the Northern Trust in New Jersey on Saturday.
While overnight frontrunners Dustin Johnson and Jordan Spieth were blown away in testing winds on the exposed Liberty National course within sight of the Big Apple, Reed carded a handy four-under-par 67.
"I did what I had to do, hitting the ball in play, missing in the right spots," the American said after signing for a 14-under 199 total.
Mexican Ancer vaulted to the front with a hat-trick of birdies from the 12th hole but then three-putted the 16th. He shot a 68 to be alone in second place in the first of three FedEx Cup playoff events on the PGA Tour.
American Brand Snedeker had the round of the day, a 63 that lifted him within two strokes of the lead on 12-under along with Spaniard Jon Rahm (69).
But it was tough sailing for halfway leader Johnson, who battled to a 74 and slipped five shots behind.
Spieth, who teed off one shot from the lead, also carded 74 on a day when poor driving, which has dogged him for much of the year, reared its ugly head again.
He was never at the races after hitting his opening tee shot into a pond.
Reed, 50th in the FedEx Cup standings, has played quite well this summer without seriously threatening to win, a 10th place at the British Open barely noticed.
"Earlier this year I was thinking too much," he said.
"There was a lot of stuff going on in my mind, whether on full swing, putting, game management. I thought I was doing a lot of things really well but the numbers were not producing."
A fine par-save at the 18th, where he recovered after driving into punishing rough, further lifted his spirits.
"There's nothing worse for me than the feeling of bogeying the last hole," Reed said. "It gives you a bad night's sleep."
Ancer, 67th in the standings, was also well pleased with his performance in the firm and fast conditions, as he hung tough in his quest for a first PGA Tour victory.
"I feel like I've been there now," said last November's Australian Open champion.
"I know what it's going to feel like. I've just got to keep my blinders on and make as many birdies as possible."
(Reporting by Andrew Both in Cary, North Carolina, editing by Ed Osmond/Nick Mulvenney)