SAN ANTONIO -- Matt Bettencourt has spent the last year searching for answers to his severe asthma problem.
The journeyman PGA Tour player found that answer last week, in the form of the right combination of medication.
His comfort showed on the golf course Thursday as he shot a 5-under-par 67 to earn a share of the lead with Peter Tomasulo, and hold off a field that includes Rory McIlroy, after the first round of the Valero Texas Open.
Minus the jitters and shakes he's become so accustomed to, Bettencourt needed only 25 putts to hold off a group of four players -- including former British Open and PGA Championship winner Padraig Harrington -- at 4 under.
The 37-year-old looked more like the former PGA Tour winner that he is rather than someone who's 183rd on this year's money list.
"My game hasn't been the concern," Bettencourt said. "... I've gone back and forth from three to four different inhalers and some different medications, which has helped my health, but I haven't been able to play golf with it at all."
Tomasulo, meanwhile, looked anything but a player fighting to keep his PGA Tour card -- taking advantage of warmer and calmer afternoon conditions while playing in the final pairing of the day.
He posted the only bogey-free round while playing in his sixth PGA Tour event of the year.
Tomasulo entered the year with the opportunity to play in eight events, thanks to a medical exemption following a rib injury two years ago, and he closed with a 10-foot birdie on the par-5 18th to earn a share of the lead -- and come one step closer to securing his tour card.
"I just played a solid round of golf to go around here with no bogeys," Tomasulo said. "We got a good end of the draw, I think, with the weather calming down late in the day."
Harrington and Billy Horschel shared the lead following the morning tee times, battling chilly and windy conditions. They were joined by Bryce Molder and Harris English at 4 under in the afternoon.
McIlroy, who entered the tournament as a final opportunity to prep for next week's Masters, opened with an even-par 72 and is tied for 45th.
Bettencourt only made the tournament as an alternate after Henrik Stenson withdrew.
Bettencourt's two-year exemption on tour ended after last season, following his 2010 win in the Reno-Tahoe Open. He had bounced between the PGA and Web.com tours this season, making only one cut in five events.
Bettencourt didn't play like a journeyman on Thursday, crediting his recent medication change that followed a hospital stay and detailed tests last October after a bout with pneumonia. His lone bogey came on No. 4, and he took the lead from Harrington with a birdie on No. 17.
Bettencourt might have found his answer away from the course, but it was Harrington who felt right at home on the course in the early morning cold and wind -- even if he didn't particularly enjoy the conditions.
The former British Open and PGA Championship winner from Ireland overcame the early morning chilly temperatures and steady wind to go as low as 5 under before finishing with a bogey on No. 18. He began his day with four layers of clothing in an attempt to stay warm as the Texas winds whipped in from the north.
"Last week back in Ireland, it was snowing, and I didn't feel as cold," Harrington said.
McIlroy, meanwhile, continued the up-and-down play that has plagued him throughout the year and cost him the No. 1 ranking to surging Tiger Woods. McIlroy was 2 under early in his round, which began on No. 10 on the difficult 7,435-yard layout, but he found the water on the par-5 18th when his approach came up short.
That began a stretch of three straight bogeys, and he missed a 7-foot par putt on No. 9 to fall back to even.
The up-and-down round was hardly what McIlroy, who has just one-top 10 finish this year, envisioned when he added the tournament to his schedule last week.
"More mental than anything else," McIlroy said. "... It's just about limiting those mistakes. It's definitely more mental mistakes than physical."
While McIlroy struggled, Horschel continued to show the form that led to a second-place finish at last week's Shell Houston Open. Horschel jumped from 60th to 24th on the money list following last week's performance, and he tied Harrington on Thursday with a final-hole birdie on No. 9.
Horschel had six birdies, including a stretch of four in five holes midway through the round, and he did so despite hitting only 7 of 14 fairways. He and Harrington had just 25 putts each, while McIlroy needed 31.
"All in all, it's a good day," Horschel said. "I could hit the ball a little bit better, but I did a good job of managing it and making a couple putts."
Ten players, including Jim Furyk, are two shots back of the lead at 3 under.