IRVING, Texas (AP) -- Sean O'Hair still gets nervous standing on the first tee.
While that anxious feeling waiting to start a round hasn't changed, a whole lot else has for O'Hair since his runner-up finish at the EDS Byron Nelson Championship two years ago. Most notably, his overall confidence.
"My game is completely different. I think I understand it more. I kind of know what's going on," the 24-year-old O'Hair said. "But it's nice to always come back here because this is kind of where I broke through. This is where I realized that, hey, I'm good enough to be out there."
O'Hair shot a season-best 5-under 65 on Thursday for a one-stroke lead over defending champion Brett Wetterich and Anders Hansen after the first round played without the tournament's namesake there.
The nervousness and strong wind on the opening hole didn't deter O'Hair, who after a strong drive hit a 5-wood to within 8 feet of the pin on the Texas-shaped green at Cottonwood Valley.
"That was definitely a sneak-away with a birdie," said O'Hair, who then added another birdie on the par-3 2nd hole.
Wetterich opened defense of his only PGA Tour victory with six consecutive pars on the TPC Four Seasons.
His 66 included an eagle 3 on the 554-yard 16th hole when he hit his approach to within 7 feet. With a chance for a share of the lead on the 440-yard closing hole, his 20-foot birdie attempt slid just left of the cup.
"On the first tee, it was nice to be announced the defending champion," Wetterich said. "Once that's all said and done, you need to focus on the golf course and hopefully play well enough to hear that again."
One of the things Wetterich treasured about winning last year was the personal congratulation he got from Nelson at the 18th green. Wetterich was the last winner to have that privilege.
Nelson, the champion golfer known as "Lord Byron" and in 1968 the first to have a PGA Tour event named after him, died of natural causes Sept. 26. He was 94.
"It is a little sad to not see Byron there. I really miss him," Phil Mickelson said after his round of 69. "But I don't think he's very far away from us. We still have all the great memories he's provided."
Luke Donald, with his ninth consecutive Nelson round in the 60s, and Scott Verplank were among five golfers tied for fourth at 67. Another dozen players posted 68s.
When O'Hair was the runner-up to Ted Purdy as a PGA Tour rookie in 2005, the story of how O'Hair's father had pushed him relentlessly to be a star became well-publicized.
O'Hair used to have to run a mile for every bogey and turned pro at age 17, a year before he finished high school.
"I kind of had my life in order. ... Once the media kind of got involved in that situation, it made it a little bit more difficult for me," O'Hair said. "That stuff is long gone, and it's been long gone for a long time."
O'Hair said he now talks to his father "once in a while," but he didn't elaborate on their relationship.
"You don't want to be known for other stuff," O'Hair said. "My life is in a great spot. I've got two beautiful kids I love to death and I've got a beautiful wife who does nothing but support me. ... I'm very fortunate to be in the situation that I'm in."
Just two months after his runner-up finish at the Nelson, O'Hair got his first PGA Tour victory at the John Deere Classic.
Since missing five of the first six cuts this season, and finishing tied for 56th in the other, O'Hair has gone back to a former instructor and had four consecutive top-15 finishes.
Mickelson also has a new teacher. But after his first round since the Masters, Mickelson didn't want to discuss the swing changes he's been working on with Butch Harmon.
"I'm pleased so far, yeah," Mickelson said. "I hit the ball well, gave a few shots back in the end."
Mickelson was at 4-under before his only three bogeys came over the final four holes.
Mickelson (No. 4), Vijay Singh (No. 7) and Donald (No. 11) are the only three of the top 13 players in the world playing this week. Mickelson and Singh,
Seven of the last eight Nelson winners played their first rounds at Cottonwood Valley, like O'Hair on Thursday. ... There were only four bogey-free rounds: Hansen, Donald, John Senden (67) and Fredik Jacobson (67), the Swede making only his third start in 2007 because of a nagging wrist injury. ... Hank Kuehne shot a 74 in his first PGA Tour round since The Players Championship in March 2006 before he had surgery on his left hip. His gallery included tennis standout Venus Williams, who he is reportedly dating. ... Friday's rounds will be the last for the Nelson at Cottonwood Valley, which has been used every year since 1994. A multimillion dollar redesign of the TPC course begins May 10.