Jason Dufner seized a two-shot second round lead at the US PGA Tour’s Transitions Championship on Friday as overnight leader Padraig Harrington failed to find the dazzling form he displayed just a day before.

Harrington, who opened the tournament with a course-record 61 on Thursday, settled for a two-over par 73 to fall two shots behind Dufner, who carded a second successive 66 to be 10-under and has yet to make a bogey on the par-71 Copperhead Course at Innisbrook.

John Senden is the best-placed Australian in a tie for ninth at six under.

Ranked 39 in the world, Dufner is the only player in the top 50 who hasn’t won on any major tour.

“It’s a good thing that I’ve played that well to be ranked that high without a victory, because the victories really jump you up in the world rankings,” Dufner, who has yet to win a US PGA Tour title in 159 starts, said.

“It’s a little disappointing that I have not won yet, but there’s a lot of events this year and next year and the year after.”

Harrington, whose 22 putts on Thursday included a 75-footer, couldn’t get the putts to drop on Friday.

The three-time major champion missed four putts from within 10 feet, taking 33 putts overall.

Harrington said he still hit the ball well, but perhaps played too defensively.

“I’m happy with my game, but when you shoot a good score, it’s hard to match the next day,” Harrington said.

“When you’re leading the tournament, it’s hard not to be a little bit cautious, and I think at times I was on the greens.”

Harrington is joined on eight under by William McGirt, who carded a 68 .

England’s Luke Donald, who could regain the world No.1 ranking with a victory this week, posted a 68 to lead a group of five players on seven under.

He was joined by South Korea’s Sang-Moon Bae (66), Ken Duke (67), Chris Couch (68) and George McNeill (68).

Harrington, who teed off on 10, held onto the lead for much of the day.

However, at the par-four sixth he marked a short putt for par, but was a bit too casual about the tap-in and missed it.

He had a three-putt bogey at seven and was suddenly two shots adrift.

“I didn’t do too much damage today,” Harrington said. “It wouldn’t have been the end of the world if I didn’t have those two three-putts. It could be OK.

Dufner birdied three of the course’s four par-fives. At the par-four third he rolled in a 15-foot birdie putt and drained a 25-footer for birdie on the par-four ninth.