Sergio Garcia and Nick Watney shared the second-round lead as a hurting Tiger Woods kept himself in the hunt at The Barclays, the first stop on the US PGA Tour's playoffs.
Garcia, riding the momentum of his win at the Wyndham on Sunday, capped his three-under par 68 at Bethpage Black with a par-saving nine-foot putt at his final hole, the par-four ninth, for an eight under total of 134.
Watney staggered home with bogeys at two of his last three holes. That included a missed seven-footer to save par at 18, but an early eagle and four birdies saw him walk off with a 69 for 134.
Woods, meanwhile, defied a sore back to shoot a two-under 69 to join a group sharing seventh on five-under 137.
Woods, who leads the playoff points standings, was clearly hurting as he made his way around the course where he won the 2002 US Open title, carefully stooping to lift the ball out of the cup.
"Must have slept funny on it," Woods said. "Soft beds at the hotel, and woke up this morning with it stiff. You know, as I warmed up, it got progressively worse, and then you saw what happened on the golf course."
Woods, who bounced back from back-to-back bogeys in his first two holes with four birdies the rest of the way, slipped in a fairway bunker at 13 and appeared to have made things worse.
"Yeah, that didn't feel very good. That didn't feel very good at all," said Woods, who nevertheless said he did not consider withdrawing and hoped to be fine Saturday after treatment.
"We have a fitness van. I'm going to go there as soon as I'm done with you guys," Woods said at his media gathering. "I'm probably going to sleep on the floor. I do that in Europe all the time, so this is nothing new."
Fijian veteran Vijay Singh carded a 67 to share third place with Bob Estes (66) on 135.
Australian John Senden (68) and Pat Perez (70) were tied on 136.
Woods was tied on 137 with Rickie Fowler (70), John Huh (67) and England's Gary Christian (71).
Overnight leader Padraig Harrington, fighting to be named one of European Ryder Cup captain Jose Maria Olazabal's two captain's picks on Monday, struggled to a 75 to fall into a tie for 16th.
Like Woods, Garcia and Watney played in the more difficult afternoon conditions.
Garcia, whose victory on Sunday ended a four-year drought on the US tour, bounced back from a bogey at the third with birdies at the fourth and fifth and parred his way home.
Watney had an eagle and a birdie on the front nine's two par-fives and had three birdies in a row starting on the 13th to counter his bogeys.