Bubba Watson played brilliant blemish-free golf over the weekend at Riviera Country Club to gain a fifth career win, the first since his 2012 Masters triumph.

Bubba Watson has produced a spectacular weekend of golf to snatch victory in the US PGA Tour event at Riviera Country Club in Los Angeles.

Sitting in a tie for 40th and eight shots off the pace at the halfway mark on Friday, 2012 Masters champion Watson closed with two blistering, bogey-free seven-under-par 64s on Saturday and Sunday to finish at 15-under and win by two strokes.

“I went into the weekend just trying to just play solid golf, just build on it, build on the future,” Watson said.

“To win around here, what an honour, what a privilege, what a blessing with the history behind this golf tournament and some of the great names as champions.”

Watson collected his fifth US tour title as he won from Dustin Johnson, who carded a closing 66.

Monday qualifier Jason Allred (68), who won more money ($US388,600) in one go then he has in his 12 years since his tour debut in 2003, and Brian Harman (68) shared third at 12-under while another Masters winner, South African Charl Schwartzel (68) was fifth at 11-under.

John Senden (70) and Aaron Baddeley (71) shared top Australian honours at seven-under in a tie for 18th.

Both Australians were left to rue a lack of momentum at critical times but took positives out of the week.

“I made a good birdie on one today but then failed to take some chances over the next several holes and that was the key,” Baddeley, who had a share of the lead early in round three, said.

“If I make a few of those I’m three-under on the round, I’m away, I’m seeing putts go in, I have momentum and it’s a different ball-game.

“But I just couldn’t get any momentum all weekend and it wasn’t to be.

“But it was great to be back in the mix, to feel the final group feelings and to once again know I’m not far away.

“Now I’m excited for the break from tournament golf to get back into the grind and fix a few little things in practice and really take things to the next level going forward.”

Senden carded three birdies in his first 11 holes to get within striking distance but the Queenslander three-putted the 12th hole for bogey before making a mess of the 13th with a double bogey.

“Holes 12 and 13 stopped my scoring run which was a shame but it didn’t really affect how I was feeling with my swing so that was pleasing,” Senden said.

“Momentum is something you need so I certainly lost it there but I was able to hang tough from that point, get a sneaky birdie late and play the last well to give me good feelings heading to Florida.

“It was my best ever result here and we got some good work done so it should set me up for the rest of the year.”

Robert Allenby (69) and Geoff Ogilvy (69) finished at four-under in a tie for 29th and Stuart Appleby (73) was the only other Australian under par for the week in a tie for 45th at one-under.

Marc Leishman (71) and Matt Jones (75) finished tied for 59th at one-over.