Palm Beach Gardens, FL (SportsNetwork.com) - Russell Henley birdied the first playoff hole Sunday to win the Honda Classic.

Henley tripped to a late double bogey en route to carding a 2-over 72 in the final round. He finished the tournament at 8-under-par 272.

Rory McIlroy, who held the outright lead at the end of each of the first three rounds, struggled with a 4-over 74 Sunday, while Russell Knox shot a 1-over 71 and Ryan Palmer carded a 1-under 69 on the Champion Course at PGA National Resort & Spa to create a four-way playoff.

McIlroy had a chance to salvage the victory with an 11-foot eagle putt at the 72nd hole of the tournament, but he could not convert and settled for a birdie to earn a spot in the playoff.

"I was fortunate that I was in the playoff," McIlroy said in a televised interview. "Even if I had won, it would have felt a little bit undeserved in a way. When you go in with a 2-shot lead here you have to play well enough to go and win the thing. If I had won today I would have counted myself very lucky."

Billy Hurley III (69) finished in fifth place at 7-under. David Hearn (67) and Will MacKenzie (70) shared sixth at 6-under 274.

Tiger Woods withdrew 13 holes into the final round, citing back spasms. He was 5-over on the day when he left the course.

"It started this morning warming up," said Woods. "I need treatment every day until Thursday to try to calm it down. We'll see how it is."

The four players returned to the 18th hole for the playoff, where Knox was the only one to not find the fairway off the tee.

Knox was forced to lay up out of a bunker, while Henley stuck his second shot onto the green. McIlroy overshot the green into a bunker and Palmer came up short with his second.

McIlroy failed to get on the green with his next, rolling his shot past the hole and into the rough. He then chunked his short chip attempt, but did sink his par putt.

Knox and Palmer each had a try for a birdie, but neither could convert.

Henley, meanwhile, had rolled his lengthy eagle putt to about three feet of the hole and rolled in his birdie effort to claim his second career win on the PGA Tour.

"I don't know what's going on right now," said Henley. "The crowd today was nothing like I have ever experienced. I wish I could play in front of a crowd like that every day. This isn't going to sink in for a while."

McIlroy had entered the final round with a 2-stroke lead over Henley, but Knox converted a 12-foot birdie putt at the first to meet Henley at 10-under.

Palmer would make it a three-way tie for second with birdies in three of his first four holes before Knox birdied the third to pull within one of McIlroy.

McIlory then stuck his third shot at the third to three feet and converted that birdie to move to 13-under and reclaim a 2-stroke lead.

After Knox bogeyed the fourth to hand McIlroy a 3-stroke advantage, McIlroy bogeyed the fourth to drop his lead back to two. McIlroy bounced back with an 11-foot birdie putt at the fifth to again reach minus-13.

Henley would lose his share of second with a bogey at the sixth before McIlroy found a bunker off the tee of the par-3 seventh, resulting in a bogey to fall to 12-under.

McIlroy found more trouble at the ninth, where he needed two shots to escape a greenside bunker for another bogey.

McIlroy later lost sole possession of first at the 12th, where he 3-putted for bogey to drop into a tie with Palmer and Knox at 10-under. Palmer had countered a bogey at the 10th with a birdie at the 12th to remain at minus-10, while Knox followed his bogey at the fourth with nine straight pars to remain there through 13 holes.

Palmer and Knox would both not be able to hang on to their share of the lead, however, as Palmer 2-putted for bogey at the 16th to fall a shot off the pace and Knox found the water with his second at the 14th, leading to a double- bogey 6 to drop to 8-under.

Henley battled back into contention with an 11-foot birdie putt at the 13th prior to chipping in from just off the green for a birdie at the 14th to meet McIlroy at minus-10.

Henley quickly lost his share of the lead after hitting his tee shot into the water at the 15th, resulting in a double bogey. He parred his final three holes to grab the clubhouse lead at 8-under.

McIlroy was next to give away his lead as he blasted out of a bunker into the water at the 16th, which led to a double-bogey to drop to 8-under and leave Palmer in first place at minus-9.

But Palmer 2-putted for bogey from five feet at the 18th to meet Henley in the clubhouse at 8-under. Knox would par his final four holes, including a 9-foot par save at the last, to also end at 8-under.

After McIlroy fell a shot off the pace with a bogey at the 17th, he birdied the last to join the playoff.

NOTES: Henley and Knox were playing in their first playoff on the PGA Tour. Palmer and McIlroy both fell to 0-2 in playoffs in their career ... Henley joins McIlroy (6), Patrick Reed (2) and Harris English (2) as players under 25 with multiple PGA Tour wins ... McIlroy was trying to join Jack Nicklaus, Johnny Miller and Mark Calcavecchia as the only multiple winners of the Honda Classic. McIlroy won the title here in 2012 ... Tim Herron remains the only wire-to-wire winner of the Honda Classic, accomplishing the feat in 1996 ... Woods is scheduled to defend his title at next week's WGC-Cadillac Championship.