Frustrating finish for Donald

Luke Donald had three bogeys in his closing four holes in a hugely frustrating end to his opening round at the Tampa Bay Championship.

Defending his title, Donald began on the back nine and was building a platform from which to make a serious tilt for another victory until the round unravelled.

From a position where he led on four under par, England's former world number one slumped back to one under and into the pack. Fives at the par-four sixth and ninth, and a four at the short eighth, did the damage.

On his final hole, Donald found rough off the tee, planted his second shot into a bunker, and even then could not find the green. He at least put the ball within five feet from his fourth shot, and made the bogey putt.

Donald was among the early starters, and one of the first into the clubhouse. On the course the lead was held by American Billy Horschel who reached four under through six, also beginning on the back nine.

Herschel's compatriots Tad Ridings, Brendan Steele and Peter Tomasulo were three under with their work done for the day, while another American, Harris English, was on the same mark through seven holes.

Vijay Singh and KJ Choi were home and hosed on two under, with Donald among 25 players on one under as play continued.

Donald was needing to buck the trend of this season to retain his title, with all 11 tournaments on the PGA Tour played so far in 2013 having been won by American players.

Horschel suffered like Donald after getting to four under, with three bogeys seeing him finish alongside the defending champion on one-under 70.

Brian Harman assumed the clubhouse lead after a four-under 67, despite a bogey on his final hole, but he was in danger of being overtaken at the end of the day by fellow US player Shawn Stefani.

Stefani was six under on the course with only the sixth, seventh, eighth and ninth to play, although as Donald could testify that was not necessarily a routine route home.