Miami - Sweden's Henrik Stenson birdied three consecutive holes and clung to a share of the lead on Friday as Tiger Woods slipped back in the second round of the PGA Tour's Arnold Palmer Invitational.
Stenson, the 2016 British Open champion and 2017 Rio Olympics runner-up, fired a bogey-free three-under par 69 to stand alongside American Bryson DeChambeau on 11-under 133 after 36 holes at Bay Hill.
Woods, a 14-time major winner and eight-time champion at the Orlando course, opened and closed the front nine with bogeys but rallied late to shoot a level-par 72 and stand seven shots back on 140 after 36 holes as he works to find consistent top form ahead of next month's Masters.
Stenson, whose only victory since his lone major title came last year at Greensboro, began on the back nine and saved pars from seven feet at the par-five 16th and 15 feet at the par-three 17th after finding bunkers off the tee.
He also sank a nervy five-footer for par at 18 after blasting out of a greenside bunker.
"Today wasn't as good as yesterday obviously but the important part for me was 16, 17 and 18," Stenson said. "I scrambled for par on all three after hitting some not-so-good golf shots, kept patient and made three in a row coming home. Three in a row on this golf course is not bad."
Stenson sank four-foot birdie putts at the par-four fifth and par-five sixth holes then dropped a 20-footer at the par-three seventh.
"My putting more than anything. I've been hitting it really close this week," Stenson said of his key to success. "If you're rolling it really good you're setting up something from three to four feet."
Staying below the hole on most greens has been pivotal, Stenson said.
"They are definitely slick when you approach on the high side and that's why you have to leave your approaches on the lower side," Stenson said.
Woods, again attempting to return in the wake of four back operations, stumbled at the start. His tee shot found the left rough and led to a bogey. At nine, Woods had a three-putt bogey from 61 feet.
"Today was just a bad day," said Woods, who dropped his approaches at the 12th and 16th inches from the cup for tap-in birdies to reach level par for the day, then narrowly missing a 14-foot birdie putt at 18.
"Today was a hard fight, it was a grind," he said. "I didn't hit the ball close. I didn't hit the ball well. but I was just hanging in there trying not to shoot myself out of the tournament."
DeChambeau, who won his first PGA title at last July's John Deere Classic, closed the front nine with three consecutive birdies, starting the run with an 18-footer at the par-three seventh.
He put his approach inches from the cup at 12 to set up a birdie and dropped a seven-foot eagle putt at the par-five 16th, then closed with a four-foot birdie putt that left him level for the lead.
American Talor Gooch was third on 135 with South Korean An Byeong-hun fourth on 136 and American Charley Hoffman another stroke adrift. Rickie Fowler headed a group of five on 138 while four-time major champions Rory McIlroy and Ernie Els were among those six strokes back on 139.
Leading second-round scores on Friday in the PGA Tour Arnold Palmer Invitational at Bay Hill (USA unless noted, par 72):
133 - Henrik Stenson (SWE) 64-69, Bryson DeChambeau 67-66
135 - Talor Gooch 65-70
136 - An Byeong-hun (KOR) 68-68
137 - Charley Hoffman 71-66
138 - Rickie Fowler 67-71, Billy Horschel 68-70, Luke List 71-67, Patrick Reed 68-70, Ryan Moore 71-67
139 - Rory McIlroy (NIR) 69-70, Ernie Els (RSA) 69-70, JB Holmes 68-71, Bud Cauley 72-67, Sam Burns 69-70, Curtis Luck 71-68
140 - Chris Kirk 71-69, Marc Leishman (AUS) 70-70, Kevin Chappell 70-70, Bubba Watson 70-70, Justin Rose (ENG) 69-71, Tiger Woods 68-72, Zach Johnson 69-71, Grayson Murray 71-69