England's Justin Rose fired a two-under par 70 on Friday to seize a share of the clubhouse lead late in the second round of the Arnold Palmer Invitational while Tiger Woods stumbled.
Rose and American Bill Haas stood on nine-under 135 after 36 holes at the $8.5 million event, which for Woods and many others is likely the final tuneup event for next month's Masters, the year's first major championship.
Woods moved within a stroke of the lead only to finish with three bogeys, a disappointing 70 leaving him in a share of seventh, four strokes behind Rose and Haas, who fired a bogey-free 66 to leap up the leaderboard.
No one still on the course was closer to the leaders than four-under par.
Rose birdied the par-3 second and par-5 sixth, 12th and 16th holes while taking a bogey at the par-3 14th and missing a five-foot par putt at the 18th to fallback into only a share of the lead with Haas.
Woods, who would become World No. 1 with a victory this week, opened with a birdie, eagled the sixth and added birdies at the par-4 11th and 13th holes to pull within a stroke of the lead.
But then everything fell apart for the 14-time major champion. He found a bunker off the 16th tee, then went into the water and missed a 27-foot par attempt to take a 6.
At the par-3 17th, Woods found the rough left off the tee, punched out 21 feet from the cup and two-putted for another bogey.
At the par-4 18th, Woods found the right rough off the tee and left himself 30 feet for par, coming up just short to drop yet another stroke.
American John Huh was alone in second on 136 with countrymen J.J. Henry, Ken Duke and Jimmy Walker sharing fourth on 138 and Woods in a pack on 139 that also included Fiji's Viji's Singh and American Mark Wilson.