FIRST ROUND LEADERBOARD:
-7 JM Singh (India), R Goosen (RSA), Prayad Marksaeng (Tha), P Mickelson (USA)-6 J Kingston (RSA), N Watney (USA), P Harrington (Ire), R Pampling (Aus)
-5 L Oosthuizen (RSA), C Villegas (Col), A Romero (Arg), S O'Hair (USA), O Wilson (Eng) -4 J Furyk (USA), C Hoffman (USA), R McIlroy (NI)
-3 L Donald (Eng), H Stenson (Swe), V Singh (Fij)-1 T Woods (USA), P Casey (Eng)
Woods struggled with his putter at the Blue Monster course
A final hole double-bogey denied Oliver Wilson a share of the first-round lead of the WGC-CA Championship.
The Englishman carded a six on the par-four 18th to finish the day on five under par, two shots behind a quartet of leaders in Doral, Florida.
Jeev Milkha Singh, Prayad Marksaeng, Phil Mickelson and Retief Goosen share the lead on seven under, with Padraig Harrington in a group one shot behind.
World number one Tiger Woods is six strokes behind the leaders.
The 33-year-old is playing in his first strokeplay event after undergoing reconstructive knee surgery in June last year.
He holed two bogeys and three birdies at the par-72, 7,266-yard Blue Monster course, but struggled to find consistency with his putter.
"It was a little bit frustrating on those greens," said Woods. "I hit so many putts that looked good.
"I thought I hit my lines and thought I had the right speed but they just didn't go in.
"It wasn't like I hit bad putts. If I was struggling on the greens then I would be a lot more frustrated but I hit good putts and they just didn't go in."
I felt going into this tournament that I was playing as well as I ever have as far as I can remember
Wilson's impressive opening round was tempered by a double-bogey six at the 446-yard 18th hole, where his second shot landed in water short of the green.
"I was more concerned missing the green right rather than left and I was just a bit in between clubs and didn't really concentrate properly and hit a bad shot," said the 28-year-old.
"It was a shame not to hole the putt for five, that would have been all right but I played all right, it was a good round apart from that so I'll try and take that forward into tomorrow and the rest of the week."
Mickelson chipped in on his final two holes to take a share of the first-round lead.
"I felt going into this tournament that I was playing as well as I ever have as far as I can remember," said the American.
"From 50 yards in, my short game has never been this good. I've never driven the ball this long and this straight without fear of a big miss.
"My iron play is better than it has been in quite some time and I expect that to improve as the week goes on."
Harrington enjoyed a prosperous day in the Florida sunshine, carding a bogey-free round featuring six birdies to move to joint second alongside American Nick Watney and Australia's Rod Pampling at the top of the leaderboard.
Northern Irish teenager Rory McIroy, making only his second appearance in America since turing professional, began his round in spectacular fashion, eagling the first and was five under after 12 holes before the 13th and 14th holes.
Fellow European Luke Donald shrugged off a wrist injury scare to card a three-under 69 while compatriots Paul Casey and Lee Westwood join Woods on one-under 71.