England's Justin Rose needed only four holes to go from three behind to joint leader on an eventful final day at the WGC-Cadillac Championship in Miami.
While Rose birdied the first and fourth - he holed from 30 feet there - Bubba Watson followed an opening two-putt birdie with bogeys at the third, fourth and fifth and did well to limit the damage to that.
The American left-hander made a 20 footer for par on the second and 25 footer for bogey at the third, where Watson found the lake.
And with the big-hitter failing to get up and down from a bunker on the short next, the second of this season's World Golf Championships was thrown wide open - even more so when he then drove wildly again into more water off the fifth tee.
Once more he scrambled well to drop only one shot, but playing partner Keegan Bradley had pitched to under two feet and, having eagled the first and bogeyed the third, the US PGA Champion joined Rose on 16 under, with Watson now one behind.
Rory McIlroy and Luke Donald, battling for the World Number One spot the Northern Irishman took for the first time with his victory in Palm Beach Gardens, were also nine under par overnight and it was Donald who made the better start.
Three birdies in his first six holes took him into a tie for fourth, but McIlroy was still on course to maintain his position at the top by picking up strokes at the first and seventh.
The drama of the day also included a hole-in-one by Paul Casey in his first tournament since dislocating his shoulder snowboarding in Colorado on Christmas Eve.
It came with an eight iron on the 15th, but even though there was a car behind the tee they quickly discovered it was a prize for an ace on the 13th.
Casey was able to laugh about it because he had agreed to give caddie Craig Connelly half of the cash value.
"I've never been so relieved," said Casey, who finished with a 73 for level par.
Bradley went two in front when he sank a 16 foot birdie putt on the seventh after Rose had failed to get up and down from sand at the previous hole.
McIlroy's third birdie came on the long eighth, putting himself back level with Donald in a share of fourth, five behind Bradley.
Just as Tiger Woods was withdrawing after 11 holes with another leg injury, the title race hotted up, and McIlroy, from eight adrift at the start, was suddenly in the thick of it.
After turning in 33 he got up and down from a bunker for birdie at the tenth and then holed out from the sand for eagle at the 12th.
Six under for the day he was only one behind not only Bradley, but also Rose. The American bogeyed the eighth after finding a horrible lie over the green and Rose birdied the tenth to catch him on 16 under.
Donald birdied from the fringe of the difficult short 13th and could not be counted out of it at three behind.
