Charley Hoffman, ice-cool on the back nine, took advantage of a last-day collapse by fellow American Ricky Barnes to clinch his fourth PGA Tour victory by one shot at the Texas Open in San Antonio on Sunday.

Two off the pace overnight, Hoffman bucked a worrying recent trend of carding poor scores in final rounds as he closed with a three-under-par 69 on the challenging Oaks layout at TPC San Antonio.

The 39-year-old Californian recorded two birdies early on the back nine to break clear of a congested leaderboard, and then held steady before sinking his winning birdie putt from nine feet at the last to post a winning total of 12-under 276.

Compatriot Patrick Reed, who played with Hoffman in the final round, had to settle for second place as he also signed off with a 69, narrowly missing eight-foot birdie putts on 16 and 17 before finishing up with a birdie at the par-five 18th.

Pádraig Harrington saw his final round challenge falter with a closing 74.

After a third round 68 left the Dubliner just four shots off the lead going into the final round he never really mounted a challenge with early bogeys proving to be his downfall. A four at the par three third hole, followed by another bogey at the next left him slipping down the leaderboard despite the fact that few players were making moves on a difficult day for scoring.

A birdie at the par five eighth hole after a superb up-and-down from left of the bunker looked as if it may get the three-time major champion back on track.

However consecutive bogeys at the ninth and 10th quickly put paid to that thought.

However there was to a late flourish in what was, overall, a poor day for the Dubliner.

A perfect drive on the 17th was followed by a beautfiul wedge shot to three feet before he rolled in the birdie putt for a late consolation and to cement a top-30 finish.