HOUSTON  - Hunter Mahan fired a final-round 71 on Sunday to win the US PGA Tour’s $6 million Houston Open by one stroke over Sweden’s Carl Pettersson. Mahan, who won the elite World Golf Championships Match Play Championship in February, became the first two-time winner on the US tour this year.

The victory will boost the 29-year-old to fourth in the world rankings, sending him into the Masters, the first major tournament of the season that starts Thursday at Augusta National, as the highest-ranked American. “It feels great,” Mahan said. “I’m playing good. I’m glad I’m going to Augusta, it’s really a special place and I’m looking forward to going there.”

Mahan’s one-under 71 at Redstone gave him a four-round total of 16-under 272. Pettersson also posted a 71 for 273. South African Louis Oosthuizen, who led by two strokes after the third round, had two double-bogeys in a three-over 75 that left him in third place on 274.

Pettersson, who closed his round with eight straight pars, notched his second runner-up finish of the year, but couldn’t get the victory he needed to secure a berth in the Masters. Three-time major champion Ernie Els also needed a victory to earn an automatic invitation to Augusta. Instead he was poised to miss the Masters for the first time since 1993 after finishing on 10-under.

“It’s not going to change my life, either way,” Els said. “I’ve played many out there. It’s one of those things.” While the Masters could still offer Els a special invitation, he said he wouldn’t accept a last-minute invitation. “To go through all of this, and then get an invite, I wouldn’t take it,” he said.

Mahan’s two birdies on the day came back-to-back at nine and 10. At the par-three ninth he drained a five-foot birdie putt. When Pettersson missed his 19-foot birdie attempt at 10, Mahan had sole possession of the lead. He gave a stroke back with a bogey from a greenside bunker at 14 then saved par from off the green at the par-three 16th, where his pitch on left him a two-footer.

Oosthuizen had opened the door early for those chasing him, starting with a three-putt bogey at the par-four second hole. He bounced back with a 45-foot birdie putt on three, but found a divot with his tee shot at the fifth and ended up missing the green. After a poor chip he two-putted for a double-bogey. At the par-five eighth he hit his approach shot into the scrub en route to a second double-bogey.