Vijay Singh has taken inspiration from Greg Norman's Open exploits and heads to the US PGA Championship insisting he feels like a 25-year-old again.

Fijian Singh fended off challenges from Lee Westwood, Stuart Appleby and Phil Mickelson to win the WGC-Bridgestone Invitational last night and declared: "I feel 20 years younger."

At 45 years and 163 days, Singh became the oldest winner since the WGC events began in 1999 as he sealed a one-stroke victory over Westwood and Appleby.

In a year that has seen 53-year-old Norman go close in the Open at Royal Birkdale and three other winners over the age of 40 on the PGA Tour - Kenny  Perry, Steve Lowery and Greg Kraft - a delighted Singh made another case for longevity.

"I always feel 10 years younger," Singh said. "Now I feel like 20 years younger.

"It shows that you can still play no matter what your age is. It's just a number."

The US PGA starts at Oakland Hills on Thursday, and Singh will start among the favourites.

The Bridgestone win was his 20th since turning 40, and his 32nd on the PGA Tour, making him the most successful non-US player of all time after going past Englishman Harry Cooper's total of 31.

"I just feel comfortable right now," he explained. "I'm not worried about being 40 or 45 or even next year for that matter.

"I have a great trainer who's taken me to the next level, and I think he's done wonders for me. I've got to give all the kudos to him. I think he really took me through a difficult program and it's showing up now.

"As you get older, I guess you just have to work a little harder, and that's what he's done to me, and I just have to thank him a lot for that. That shows that if you're physically fit, you can play as long as you want to play.

"Look what Greg Norman did. He looks pretty much the same as he did when he was playing the tour. He's as fit as he ever was."