WGC Cadillac Championship, Florida par=72: -8 H Mahan (US) -7 R Ishikawa (Jpn) -5 N Watney (US), C Hoffman (US), M Laird (Sco), L Donald (Eng) -4 S Stricker (US), F Molinari (It), T Aiken (SA), A Scott (Aus), M Kuchar (US), K Streelman (US), DA Points (US), V Singh (Fij), R McIlroy (NI), P Harrington (Ire)
Selected others: -3 R Fisher (Eng), R Goosen (SA), E Els (SA) -2 T Woods (US), G McDowell (NI), P Casey (Eng), L Westwood (Eng)
Kaymer replaced Westwood (behind) as world number one
Martin Kaymer's quest to remain world number one began well when the delayed first round of the WGC Cadillac Championship in Florida was completed.
Kaymer returned a 66 when the round, restricted by a storm to 10 holes on Thursday, was completed.
Playing partners world number two Lee Westwood and world number three Luke Donald shot 70 and 67 respectively, and Scotsman Martin Laird also carded a 67.
Hunter Mahan leads by one shot from Ryo Ishikawa after an eight-under-par 64.
Rory McIlroy dropped a 22kg dumb-bell on his big right toe during a fitness session but was able to record a round of 68 at the Blue Monster course.
"It's sore, but it's fine," he said. "I was just putting it [the weight] back on the rack and it just slipped off."
Another Northern Irishman Graeme McDowell, the world number four, finished six shots off the lead at two-under.
His playing partners Tiger Woods and Phil Mickelson had contrasting finishes. Woods, who hit a seven-iron from 210 yards to the green of the par-five 8th to set up a birdie, finished his round with a par for a two-under 70.
But Mickelson dropped to one over after a wretched end to his round.
The world number six saw his tee shot on the 8th hit a cart path and fly into the water. His next shot caught a slope and went into the water again for a double bogey in a round of 73.
Westwood collected a much needed birdie at the last having dropped shots at the 12th, 13th and 15th - all as a result of finding bunkers.
Laird reached six-under after chipping in at the 5th, his 14th, and pitching to six feet on the next, but he bogeyed the next and finished alongside Donald, who also got to minus six only to three-putt for a bogey at the last.