In-form Jason Dufner remained on track for a third PGA Tour victory in four weeks by surging into an early lead in yesterday’s second round of the Colonial Invitational in Fort Worth, Texas.

Dufner, who won his second title on the US circuit at the Byron Nelson Championship on Sunday, fired a flawless six-under-par 64 on another hot and breezy day at the Colonial Country Club.

Dufner reached 27 of 36 greens in regulation over the first two rounds. He covered his last nine holes in four-under 31 to post an 11-under total of 129, four better than the completed round of Bo Van Pelt (64).

Fellow American Tom Gillis (69) was a further stroke back at six under. First-round leader Zach Johnson was eight under after 15 holes. Tommy Gainey, with two holes to play, was also eight under.