"Everyone keeps asking me why I play so well in match play but don't perform in strokeplay," said the 36-year-old, the first Englishman to win two WGC events after his 2010 Accenture Match Play Championship win. "I think I do perform well but obviously don't have that killer instinct that I have sometimes in match play and that's a mindset that I need to build up.

"I've done exactly that this week … it's all added up into a victory. I guess I know I can do it in strokeplay, it's just a case of doing it week-in, week-out."

Poulter's 21-under total was the new low score for the tournament and the third-lowest total by a winner in WGC history. He pocketed US$1.2 million, but had spent the winnings last week before they were even earned: "Yes it was expensive, and yes it's a vehicle."

Poulter said he was still drawing inspiration from the Ryder Cup and the next step is to try to win a major. "I'm definitely riding that wave, and hopefully I can continue with the confidence that I've got from the Ryder Cup to just bottle as much of it as I possibly can and use that in strokeplay events.

"I'm at the stage of my life and career where I've won some big tournaments and obviously this is going to go down as another.

"I know I've got the golf game to be able to go out there and win majors. People keep asking all the time: When, when, when. I don't know when, and I'm trying really hard and obviously I'd like to put one in the trophy cabinet, simple. But I'll do my best next year and see if I can do that."

Poulter has only had one winless season and his eight-birdie, one-bogey display continued that run. He was 15 under for the front nine over his four rounds, getting better throughout the week in shooting 69, 68, and two 65s. He had only four bogeys all week.

Overnight joint leaders Lee Westwood and Louis Oosthuizen went round in 72 and never challenged.

A log jam at the 15th saw Poulter drive with Mickelson looking over his shoulder, and he highlighted his birdie there as key. He bogeyed 17 to let Mickelson back in and it looked like a US-Europe play-off could take place, but Mickelson also bogeyed 17 and Poulter nervelessly got up and down from the sand to par 18.

"The birdie on 15 was huge," Poulter said. "Phil's standing on the tee box as I'm teeing off so it was crucial to birdie. Once I was through 17 I didn't realise until I hit that bunker shot [third on 18] that Phil had bogeyed as well so that made the closing putt a little easier."

Mickelson felt he had to take risks as he watched Poulter up ahead. "I saw what he was doing," said the two-time winner of this event. "I was aware. I knew I needed to make some birdies. I tried to carve a few shots into some of the pins and wasn't able to get close enough. But he played really well, and I felt like these four days, I played some good golf and I'll hopefully improve on it [at this week's Barclays Singapore Open]."

Mickelson's 68 saw him finish 19 under in a tie for second with Jason Dufner (64), Scott Piercy (65) and Ernie Els (67), impressive in his first tournament back after an ankle injury. Oosthuizen and Westwood were one shot farther back.

Japan's Hiroyuki Fujita (67) and Thailand's Prom Meesawat (68) were the top Asians, finishing joint 11th at 14 under.

China's Liang Wenchong had a 68 to finish on nine under (joint 24th), but Wu Ashun had his first over-par round (75), to slip to four under (joint 36th).