LOS ANGELES -- The PGA Tour's preeminent snowboarder, David Duval, returned refreshed from the slopes and quickly got back into his remarkable golf groove.
Duval, whose game has been mostly phenomenal for the past nine months, shot an opening 5-under-par 66 Thursday to share the Nissan Open lead with Bob Estes.
Going for his third win in five 1999 starts, Duval toured Riviera Country Club without a bogey and came close to dropping a shot to par only on No. 14, where he made a 7-foot par putt.
Estes, whose only tour win was the 1994 Texas Open, had seven birdies and two bogeys on the way to his 66.
The co-leaders didn't have much margin for error, with a group of players, including Nick Price, just a shot behind, and a host of others, two-time champion Fred Couples and Ernie Els among them, two strokes back with 68s.
Tiger Woods, coming off a win at San Diego over the weekend, also was close with a 69.
Duval, who came back from an earlier ski trip and won the Bob Hope Classic with a tour-record closing round of 59 last month, believes getting away from golf for awhile helps keep him sharp.
"You get into some good (snow) powder and you kind of float on the top, there's almost no sound, it's a great feeling, an unbelievable feeling," said Duval, who added that he's pretty much gave up his skis for his snowboard while at Sun Valley, Idaho, last week.
"I'm really glad I like doing that, because when I get back (to golf), it reminds me just how much I love the game."
Duval has been the tour's dominant player for the last nine months, winning nine of his last 30 starts.
Asked if he thought he was going to play well every time out, he replied, "That's certainly my intention. And I think feeling that way helps you to play well."
Estes, 33, says he's still learning by observing other players, including Duval.
"I've learned a lot by watching Tiger, David and Justin (Leonard)," Estes said. "I've learned, among other things, to strengthen my left-hand grip.
"I've always had one of the best short games, but until my ball-striking gets better, I'm not going to be where I want to be, to win. I don't try to fool myself or anybody else; I haven't learned to play under pressure like those guys."
Couples, who won the tournament in 1990 and 1992, and finished second in 1993, 1994 and 1996, obviously feels at home at Riviera, where he also is a gallery favorite.
"I love the course," he said. "I can't beat Tiger or Duval on most courses, but I think I can on my favorite course."
Billy Mayfair, who edged Woods in a playoff for the Nissan title a year ago, was even with him again with an opening 69 this time.
Paul Lawrie of Scotland fired a 7-under 65 Thursday and took a two-stroke lead halfway through the $1 million Qatar Masters.
Lawrie had a 36-hole score of 11-under 133 over the 7,260-yard, par-72 Doha Golf Club.
Play included holes-in-one by England's John Bickerton and Sweden's Patrik Sjoland. Bickerton was tied for second with Frenchman Jean Van de Velde and Denmark's Soren Kjeldsen at 135.
First-round co-leader Raymond Russell shot a 70 for 136. The other first-round leader, Marc Farry, had a 75 for 141.