Westwood has previously hit a 63 on the Firestone in Ohio

England's Lee Westwood is two shots off the lead of Vijay Singh after the second round of the WGC-Bridgestone Invitational at Firestone, Ohio.

Westwood fired a 65 to join a group on five under par, one shot adrift of Phil Mickelson, who carded a 66, the same as 45-year-old Fijian Singh.

Westwood said he was confident after his tied-third finish at the US Open.

"It's not going to get any more pressurised than playing in the last round of the US Open," he said.

"I have tried to carry on the confidence that I built up here into this event."

The 35-year-old started the day four strokes off the pace but birdies at the first two holes set the tone for his second-round charge on a course on which he has previously fired a 63.

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"The first holes were nice and painless," the former world number four said. "I hit a driver and wedge to about 12 inches at the 10th, which was my first hole, and then driver, wedge to about eight inches on 11.

"It doesn't get much easier than that to start a round. My overall game tee to green was very good."

Singh revealed that Greg Norman's success at the Open Championship had given him the inspiration to continue striving late into his career.

The three-time major winner is just five years away from the senior tour and eight years younger than former world number one Norman, who finished in a tie for third at Royal Birkdale.

"I was pulling for him," Singh said. "It's one of those tournaments where you don't think how young, how old you are, you just kind of manage to get through those conditions. That's why he played that well."

Singh missed the cut at Birkdale and went back to his home at TPC Sawgrass in Florida to watch the weekend drama unfold.

It [Greg Norman's Open performance] was good for all the Senior Tour players and obviously the older generation guys, myself, Kenny Perry and those guys, that you can still compete past 50 Vijay Singh

"I talked to a lot of senior golfers that were at TPC that week, and they were all excited about it," he said.

"They said it gives all the guys hope that they can go out there and still do it.

"In that respect I think it was good for all the Senior Tour players and obviously the older generation guys, myself, Kenny Perry and those guys, that you can still compete past 50."

Two-time Open champion Padraig Harrington carded a second-round 75 that left him at four over for the tournament and he admitted his focus was now on next week's USPGA at Oakland Hills near Detroit.

"It's all about next week now," Harrington said. "It's all about getting my chipping right out of the rough, going to do a bit of practise on that, and just getting myself into the mindset for next week.

"So I'm happy about having another two rounds, opportunities for that, but as far as that I'm not going to overdo things. There's no question I'm suffering a bit with fatigue."

Harrington admits that winning the Open has taken its toll on his game but Birkdale runner-up Ian Poulter said he was still on a high.

"No, I'm not flat, I'm buzzing," Poulter said following a second-round 68 that leaves him at two under par.

"I was pretty refreshed. It was a long week off the week afterwards, so I'm just trying to get through the next two weeks as good as I possibly can and put myself in the Ryder Cup side. I'm still charging."