Australian golfer Jason Day has once again shaken off the loss of his regular caddy and coach Col Swatton to push into a tie for second after the second round of the lucrative US PGA Tour Championship.

Day carded a three-under-par round of 67 to jump to six under for the tournament, leaving the Queenslander two shots behind leader and last start winner Billy Horschel.

Horschel was a shot better on the round with a 66 while world No.1 Rory McIlroy shot 65 to be a looming presence on the boards with Day and current FedEx Cup points leader Chris Kirk (68) at six under.

Swatton was due to return to Day’s bag after pulling out through seven holes on Thursday with a hip joint injury but was a late scratching Friday, forcing mental coach Jason Goldsmith to once again step into the role.

But the pair didn’t miss a beat, going bogey free until the very last hole.

Three birdies in his opening five holes put Day top of the boards early and, while he cooled with eight straight pars, another birdie at 14 ensured he continued his charge.

The final-hole bogey was his only blip.

It was tougher going for the other Australians.

World No.2 Adam Scott continued his worrying trend of not being able to put four rounds together, shooting 72 Friday to drop to one over par and into a tie for 16th.

Scott was three over on his first seven holes but had clawed his way back to even through 15 holes until an ugly double bogey on the 17th tomahawked his chances.

“I was disappointed with 17, it was a poor swing and a tough time to do it so now I have to hope the leaders have a tough weekend and I have a good one,” Scott said.

The tournament is already out of reach for John Senden (75) and Geoff Ogilvy (77) as they hold the last two positions in the 29-man field with Senden seven over and Ogilvy a distant last at 14 over par.