Jason Day appears to have found a semblance of his best form among a host of Australians well placed after the first round of professional events in the United States overnight.

Day and the in-form Matt Jones head the Aussie PGA Tour contingent at the Workday Charity Open in Ohio, with both carding 69s to sit four behind early leader Collin Morikawa in a share of 18th.

Day closed with a birdie on the ninth hole at Muirfield Village after seeing his early progress frittered away with bogeys on the seventh and eighth.

But his six-birdie round is one of the best signs possible his recent slump is nearing an end. Jones, too, was within touching distance of the lead before two late bogeys, but was again impressive.

Marc Leishman (72), Cameron Davis (73), Aaron Baddeley (74) and Cameron Percy (76) have work to do to return to contention.

On the Korn Ferry Tour, Ryan Ruffels has bounced from the blocks with a stylish 67 to share eighth place just three from the lead after round one of the San Antonio Challenge.

Fellow young Aussies Curtis Luck, Brett Coletta and Harrison Endycott carded 70s to share 54th, while veteran Rob Allenby found a little form to sign for a 71.

Brett Drewitt sits a shot further back, but Steve Bowditch will need a miracle after an opening 81.