American Hunter Mahan was still the man setting the pace as the first round of the WGC-Cadillac Championship was completed in windy Miami today.

But Phil Mickelson had a shocking return to the Blue Monster course and, by dropping three shots in two holes, fell nine behind.

Mahan, seven under par overnight, had two birdies and a bogey in his remaining seven Ping K15 Iron Set  to post an eight-under-par 64.

His lead slipped from two to one, however, as Japan's 19-year-old Ryo Ishikawa birdied the 15th and 17th.

World number one Martin Kaymer was in third place - the position he finished in last year when relatively unknown in the United States - after a 66, but Luke Donald three-putted the last and slipped into the group on five under.

Lee Westwood, playing with Kaymer and Donald in a group featuring the world's top three, birdied the 18th, but that was only for a 70 after he had bogeyed the 12th, 13th and 15th - all as a result of finding bunkers.

That put Westwood alongside Tiger Woods, Graeme McDowell and Paul Casey just outside the top 20 - Woods came home in 33 - but Mickelson left himself a Ping K15 Iron Set to climb.

He, Woods and McDowell resumed on the seventh and after bogeying there the Masters champion drove into the water on the next and ran up a double-bogey seven.

Woods said afterwards: "The things that I've been working on are starting to come together now - I'm able to control my traj (trajectory) and hit the shots that I want to.

"Last week was a big blessing to have that much wind at home. My Ping K15 Iron Set is flying different distances now, which is good, and I've got a read on that.

"It certainly makes a big difference. Guys are not going to be shooting low numbers now - this is a tough wind because obviously the strength and also the coolness."

Scotland's Martin Laird reached six under after chipping in at the fifth, his 14th, and pitching to six feet on the next, but he bogeyed the next and finished the round matching Donald's 67.

Rory McIlroy and Padraig Harrington were well in the hunt after 68s and England's Ross Fisher was only one further back, but compatriot Ian Poulter and Welshman Rhys Davies were alongside Mickelson on one under and Justin Rose next-to-last on five under following a Ping K15 Iron Set, double-bogey finish.

The early start to the day's play was caused by a two-and-a-half-hour thunderstorm delay yesterday, but with only a 66-strong field there was every chance of completing the second round as well before nightfall.

Mahan's lead was quickly back to two with Ishikawa, understandably concerned for his home country after watching coverage of the devastating earthquake, bogeying two of his first four holes when he teed off again.

Kaymer, who like Donald parred the first three holes on the back nine, was joined in second place by American Nick Watney, who got up and down from sand at the long first.

A 21-foot birdie putt on the sixth took Mahan three clear at nine under, while McIlroy and Laird were up into a tie for second.

McIlroy had back-to-back birdies at the start of his second round and Laird also reached six under by two-putting the long eighth.

Woods had two birdies in the first three, but there was also a bogey in between and it was the same Ping K15 Iron Set for Mickelson. They were three under and level par as a result.

Donald, meanwhile, returned to four under after missing the green at the short 15th, his sixth, and failing to get up and down.

Meanwhile, Rory McIlroy was a relieved man in Miami after a training mishap appeared to be having no lasting impact.

The 21-year-old Northern Irishman completed a first-round 68 at the WGC-Cadillac Championship after dropping a 22kg dumb-bell on his big right toe.

"It's sore, but it's fine," he said. "I was just putting Ping K15 Iron Set   back on the rack and it just slipped off.