Westwood, who lost to McIlroy in the semifinals of the Match Play Championship in February, caught him with a birdie on the par-3 13th. But the weak area of his game showed up at the wrong time — a poor chip on the 14th for bogey, another pedestrian chip on the par-5 15th that led to par. He wound up with a 69.
"I played with him when he was 13, and you could see it then," Westwood said. "He's just maturing all the time, as he will do. And he's a very, very good player.
Mickelson, tied for the lead going into the final round, was one shot behind when his approach flew the green on No. 12 and he had to scramble for bogey. Mickelson made back-to-back birdies late in the round to get within two shots of the lead, but he badly missed a 3-foot par putt on the 17th to fall three shots behind. He closed with a 70.
"A lot of people stayed neutral and Rory geared ahead," Mickelson said.
Woods was never seriously in the mix. Five shots behind with seven holes to play, he made three late birdies and shot 68 to tie for fourth with Robert Garrigus (69).
McIlroy's work is not done.
He is the No. 1 seed going into the FedEx Cup finale in two weeks at East Lake, but any of the top five seeds can win the Tour Championship and capture the FedEx Cup with its $10 million bonus. The other four seeds are Woods, Nick Watney, Mickelson and Brandt Snedeker.
"Rory is putting on a show out there," Woods said. "And we've got one more tournament."
Any of the top 30 players who advanced to the Tour Championship have a mathematical shot at winning the $10 million prize. One guy who won't have that opportunity is Vijay Singh, who started the final round tied for the lead with Mickelson. The 49-year-old Fijian fell apart on the back nine with three bogeys in a four-hole stretch to fall out of the top 30. A birdie on the final hole gave Singh a 73, but by then it was too late.