Phil Mickelson came up short in a US Open for a record fifth time as Lucas Glover held his nerve to claim a two-shot victory on a dramatic final day.

Glover had started the day with a five-shot lead over the field at seven under par alongside co-leader Ricky Barnes as the rain-delayed championship moved into a fifth day at Bethpage Black.

Barnes disintegrated with six bogeys in seven holes and Glover was caught by Mickelson and David Duval at four under and three under, while England's Ross Fisher also challenged.

Yet his rivals fell away at the most crucial time of all, all bogeying either the 15th or 17th holes or both as 29-year-old Glover stayed calm to win at the 109th US Open.

"I didn't expect this on Thursday, to say the least," Glover said. "But I was playing well coming in and I knew if I put four (rounds) together I might have a chance.

"It feels pretty good...obviously I'm very excited and just happy I hung in there."

Glover, with one previous victory on the PGA Tour in 2005, won his first major with a one-birdie, four-bogey final-round, three-over 73, good enough to hold off Mickelson (70), Duval (71) and Barnes (76) by two strokes.

Mickelson, who moves ahead of four-time runners-up Jack Nicklaus, Arnold Palmer, Robert Trent Jones Jr and Sam Snead, will now step away from the game to be with his wife Amy, who begins treatment for breast cancer on July 1.

"Certainly I'm disappointed, but now that it's over, I've got more important things going on, and, oh well," Mickelson said.

Fisher claimed fifth, his best majors finish, a further shot behind following a 72 with 2008 winner Tiger Woods tied for sixth at level par alongside fellow American Hunter Mahan and Denmark's Soren Hansen. Rory McIlroy finished in a tie for 10th on his US Open debut.

The tournament had been blown wide open by a final-round collapse from third-round leader Barnes.

The Californian, without a victory in six years as a professional, saw his final round implode.

When play resumed today, the first time since 1983 a US Open had needed an extra day to complete 72 holes, Barnes found the second green out of the rough to make par.

Fisher, runner-up behind Paul Casey at last month's BMW PGA Championship at Wentworth, rolled in a three-foot birdie putt at the par-five fourth to get back to three under - four shots behind Barnes - with Glover bogeying the third to slip to six under.

World number two Mickelson bogeyed the sixth and Duval, in the wilderness since his 2001 Open victory at Lytham, was quickly in trouble with a triple bogey at the par-three third.

However, he sunk a birdie at the par-five fourth to get back to level par - and would stick around for the rest of the day.

Everything changed when Barnes began to slide back towards the field. He and Glover bogeyed the fifth hole but Barnes would bogey three more in succession to fall to three under after eight as Glover assumed the lead at five over.

Then Glover bogeyed the ninth and was leading at four under after 10 with the tournament wide open.

Fisher had bogeyed the fifth and the seventh to drop to one under but a super iron shot to inside two feet led to a birdie and after nine holes he was within two shots of the lead at two under.

Mickelson had also been in trouble, bogeying the sixth and the eighth to fall to level par but he birdied the ninth as Barnes fell apart - then the four-time runner-up got to two under with a birdie at the 12th.

Fisher sent in another great approach shot at 12 but missed the par putt from inside two feet to fall back to one under.

Mickelson made the first eagle of the tournament on par-five 13 to join Glover in a share of the lead at four under.

Fisher swiftly added the second eagle there to bounce back in style at three under, one off the lead with five to play as Barnes went further backwards at the 12th with his sixth bogey in seven holes.

On an ever-changing leaderboard, Mickelson bogeyed the 15th to drop to three under and Fisher followed to fall to two under while Duval shot a rare birdie to get to the same mark.

"I think I'll probably go home and work on my putting," Fisher said. "Not being funny, but if I would have held just a couple of putts, I think I could have won this comfortably.

"I feel like I've hit the ball so, so well; probably the best I've hit it ever in a tournament. I just couldn't hold any putts."

Glover bogeyed 15 and fell into a joint lead with Mickelson at three under - who sank a par putt at 16 at exactly the same moment.

Duval made it a three-way lead with a third successive birdie at the 16th - but he and Mickelson bogeyed the par-three 17th.

At that point Glover managed to score his first birdie of the day at the 16th and the 29-year-old was back in front at four under with two to play, two shots to the good for a lead he would not relinquish.

Defending champion Woods got to one under but a bogey at the difficult par-four 15th ended hopes of a fifth US Open title and 15th major victory.

"I had a chance today, I birdied 13, 14, and hit the best shot I hit all week at 15," Woods said. "I just ended up making bogey there.

"Then I gave myself chances on the last three holes. I hit an eight iron right underneath the flag right where you need to leave it, striped a four iron. And on 18 I had to be a little more conservative because of where I was. But overall, I gave myself so many chances and made nothing."

McIlroy's 68 left the Northern Irishman at two over, while Graeme McDowell and Ian Poulter were part of a tie for 18th place at four over. Lee Westwood and Oliver Wilson ended on five over in a tie for 23rd.

Collated final-round scores (USA unless stated, par 70):

276 Lucas Glover 69 64 70 73

278 Ricky Barnes 67 65 70 76, Phil Mickelson 69 70 69 70, David Duval 67 70 70 71

279 Ross Fisher (Eng) 70 68 69 72

280 Hunter Mahan 72 68 68 72, Tiger Woods 74 69 68 69, Soren Hansen (Den) 70 71 70 69

281 Henrik Stenson (Swe) 73 70 70 68

282 Rory McIlroy (NIrl) 72 70 72 68, Mike Weir (Can) 64 70 74 74, Sergio Garcia (Spa) 70 70 72 70, Matt Bettencourt 75 67 71 69, Stephen Ames (Can) 74 66 70 72, Ryan Moore 70 69 72 71

283 Anthony Kim 71 71 71 70, Retief Goosen (Rsa) 73 68 68 74

284 Peter Hanson (Swe) 66 71 73 74, Michael Sim (Aus) 71 70 71 72, Graeme McDowell (NIrl) 69 72 69 74, Ian Poulter (Eng) 70 74 73 67, Bubba Watson 72 70 67 75

285 Steve Stricker 73 66 72 74, Sean O'Hair 69 69 71 76, Oliver Wilson (Eng) 70 70 71 74, Lee Westwood (Eng) 72 66 74 73

286 Francesco Molinari (Ita) 71 70 74 71, Vijay Singh (Fij) 72 72 73 69, Azuma Yano (Jpn) 72 65 77 72, J.B. Holmes 73 67 73 73, Stewart Cink 73 69 70 74, Johan Edfors (Swe) 70 74 68 74

287 Jim Furyk 72 69 74 72, Kevin Sutherland 71 73 73 70, Camilo Villegas (Col) 71 71 72 73

288 Adam Scott (Aus) 69 71 73 75, Todd Hamilton 67 71 71 79, Carl Pettersson (Swe) 75 68 73 72, Nick Taylor (Can) 73 65 75 75

289 Dustin Johnson 72 69 76 72, Billy Mayfair 73 70 72 74, Tim Clark (Rsa) 73 71 7471, Drew Weaver 69 72 74 74

290 Kenny Perry 71 72 75 72

291 John Mallinger 71 70 72 78, Thomas Levet (Fra) 72 72 71 76

292 Andres Romero (Arg) 73 70 77 72, K J Choi (Kor) 72 71 76 73, Gary Woodland 73 66 76 77, Tom Lehman 71 73 74 74, Geoff Ogilvy (Aus) 73 67 77 75, Rocco Mediate 68 73 79 72

293 Kyle Stanley 70 74 74 75

294 Jean-Francois Lucquin (Fra) 73 71 75 75, Angel Cabrera (Arg) 74 69 75 76, Andrew McLardy (Rsa) 71 72 75 76

296 Ben Curtis 72 71 74 79

297 Jeff Brehaut 70 72 81 74, Trevor Murphy 71 69 77 80

301 Fred Funk 70 74 75 82