Earlier this year, Couples hinted that he might retire from the sport if his game did not show signs of improvement. He started on the back nine of the Southern Highlands course and made the turn in 4-under 32. He promptly birdied the first three holes on the front nine and wound up with birdies on all par-3 holes.
Couples has not won a PGA Tour event since the 1998 Memorial. He has failed to crack the top 10 in any of 17 tournaments this season, has missed the cut five times and is just 130th on the money list with $354,066.
Lehman, playing at the TPC-Summerlin course, birdied four straight beginning at the 13th to get to 9-under for the day.
Howell began the year playing on the European Tour in that circuit's stops in Australia. Without being an exempt player on the PGA Tour when the season began, Howell has played his way into the No. 10 position on the money list.
John Daly, meanwhile, opened with a 67. Daly has been one of the hottest golfers in the world over the past month. He won the BMW International, finished second at the German Masters and was fourth at the Canadian Open.
He has climbed to 56th in the world rankings and likely would need only one more high finish this year to end the season in the top 50 -- which would earn him an invitation to next year's Masters. Daly, the only high-profile American player to compete overseas since the Sept. 11 terrorist attacks, turned down an invitation to compete this week at the Cisco World Match Play Tournament in England.