Watney, who set a course record Saturday with a 62, finished 72 holes at 13-under 267, 3 strokes lower than Justin Rose's winning score last year. Choi, who tied for the lead after a birdie at the 14th hole but followed it up with a crushing double-bogey at No. 15, shot a 67 to take second at 269.
The game didn't look as easy Sunday for Watney as it did on Saturday's back nine, where he shot a 27, one off the PGA Tour record for a nine. He hit just seven fairways and 11 greens but kept his score on the low side with 26 putts. Obviously, he handled the pressure just fine.
"I guess it all goes back to the PGA last year," he said. "Definitely the moment got the best of me, and I performed very badly. But I really feel like I learned a lot that week, especially Sunday. I knew today was going to be a long, hard day."
Watney held a 3-stroke lead going into the final round of the 2010 PGA at Whistling Straits on the Wisconsin shoreline of Lake Michigan, but he skied to an 81 in the final round to wind up 7 strokes out of the playoff for the championship.
He has rebounded from that low point to become perhaps the most consistent player on the PGA Tour this season. He won the World Golf Championship-Cadillac event last March at Doral and had six other top-10 finishes before this week. On Sunday, his fourth career win, worth $1,116,000, boosted his 2011 earnings to almost $4.2 million.
Watney played in the final group with Rickie Fowler, who shared the three-round lead with him, and Choi, but it was Choi who kept the heat on throughout. Still, Watney's putting was strong.
On the front nine alone, Watney hit only four greens in regulation but had 10 putts. He drained a 25-foot putt for par at No. 4 and sank a 20-footer for birdie at the fifth. He drove into the trees at No. 6 but left with a par after a six-footer and got up and down out of a bunker at the seventh.
"I put a new putter in the bag this week, a Scotty Cameron," he said. "I couldn't putt it in the ocean [last week]. But I was seeing the lines really, really well. . . . It was fun to putt like that under pressure."
Choi was 3 shots back at the turn but made it a contest with birdies at 10, 11, and 14 - the last one on a 30-foot putt - to move into a tie at 12-under.
However, at the 15th, a brutish 503-yard par-4, Choi drove in the left rough, knocked his second shot into a bunker 50 yards short of the green, and missed the green with his third, winding up with double-bogey.
Choi said he caught too much grass with his 5-wood second shot, and he had a bad lie in the bunker.
"When I tied him on 14, I knew the remaining holes were more favorable to Nick," Choi said. "That [15th] was a key hole . . . the turning point of the match."
After both men birdied 16, Watney missed the green long at the par-3 17th but made par. He hit the 18th with his approach and then watched with a few nerves as Choi's 25-foot birdie try burned the left lip.
"If K.J. makes that, my four-footer gets a lot longer," Watney said.
But it stayed the same length and Watney knocked it in. Mission accomplished.
"There have been times when maybe I was a few shots back and trying to make a charge," he said. "So I think it's a process, but I really do love to be in the last group and play when it really matters."
The 22-year-old Fowler, in his second tour season, still has to get there. He took a couple of steps back almost immediately with a double-bogey at No. 2 and never recovered, shooting a 74 to drop to a tie for 13th at 275.
Still, it was Watney's day.
"Nick just played too well today," Choi said. "He played like a champion."
Contact staff writer Joe Juliano at 215-854-4494 or firstname.lastname@example.org.