Atwal shot 66 with five birdies and one bogey and ended with a total of three-under 274. It was his second round in the 60s, following his first round 67.
"I'm getting better. All the changes I've made are finally starting to feel comfortable," said Atwal, who is in the midst of remodeling his golf swing.
Atwal, tied 39th overnight, had birdies on the third and sixth and turned in two-under. A bogey on 14th was followed by birdies on 15th, 16th and 18th for a round of 66.
While he had a great time with the putter, needing just 23 putts in first round, the final round was highlighted by 83 per cent greens in regulation, though he needed 29 putts.
Meanwhile, Noh Seung-Yul, the 2010 Asian Tour Order of Merit winner, also shot 66 and finished at six-under 274 to be tied seventh, just three shots behind winner, Dustin Johnson.
Daniel Chopra shot a final round of 71 and at one-under 279 he was tied 27th.
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Johnson won in only his second event after returning from a back injury that cost him three months. He shot a final round 66 and beat John Merrick by one shot.
He pulled a muscle in his lower right back in early March lifting a jet ski at his home. He was forced to rest to recover and returned to the Tour last week at the Memorial Tournament where he tied for 19th.
Johnson led by only a stroke going to No. 18. Rory McIlroy, Chad Campbell and Nick O'Hern, three of the four who had a chance to tie Johnson with a birdie, put their tee shots into the lake. Johnson made sure he hit the fairway to at least give himself a chance at birdie. Par was good enough.
McIlroy finished in a tie for seventh. Davis Love III, the U.S. Ryder Cup captain, shot a 69 and tied for third with O'Hern (69), Campbell (68) and Ryan Palmer.