Reigning British Open and PGA champion Padraig Harrington had a disappointing start to the Buick Invitational and sits eight shots off the lead.
Harrington was three-under through the turn, but his inward run included a double-bogey and bogey before a birdie at 18 saw him finish on 71.
Harrington began his year with a fifth place finish at the Abu Dhabi Championship before having two non-malignant melanomas removed from near his right eye less than two weeks ago.
Colombian Camilo Villegas fired a nine-under-par 63 to take the lead after the first round.
A winner of two events last year including the Tour Championship, Villegas is three shots ahead of Davis Love III and Aaron Baddeley with Stuart Appleby, Jeff Overton and Robert Garrigus at four under after carding eight birdies and one eagle.
A group of nine players sit at three under, just ahead of three-time winner Phil Mickelson who carded an opening round 70.
'It was a pretty fun day. I had two chip-ins, that helps. I had one on number two for eagle and then a nice one on 17 to finish the round. But even if you take the chip-ins out, I played pretty good,' said Villegas.
'I drove it nicely. I hit some great shots and left myself some good opportunities. It's not easy to have a good short game on that golf course today. The greens are bumpy, and you've just got to be really committed to your line, and that's exactly what I did today.'
