Jason Day has produced a birdie blitz around the turn to take the lead from fellow Australian Matt Jones late in the third round of the US PGA Championship at Whistling Straits.

Day birdied the ninth and 10th holes, eagled the 11th and birdied the 13th to push to six-under on his round and 15-under for the championship, two clear of second round leader Jones.

The pair have played 13 holes with Jones two under on Saturday to be 13-under.

South African Branden Grace shot an eight-under-64 to get in the clubhouse at 12-under where he is joined by American Tony Finau who is still on the course.

Jones opened the third round with a two-stroke lead and increased it to three on the front nine only for it to close at the turn.

The Sydneysider almost holed out for eagle on the opening hole but tapped in for birdie and then added another from 10 feet on the sixth.

A wild drive left on the ninth into a hospitality tent had Jones playing from carpet amongst the fans and although his recovery shot was within half a metre of holding the green it sat down in deep rough and a bogey ensued.

It allowed Day to bury a 12-foot birdie on the same hole to move within one.

Earlier Day matched Jones on the first with an even closer approach but then rode a rollercoaster by going bogey, birdie, bogey, birdie on his next for holes.

The world No.5 steadied on the ninth to get back amongst it and then went on his tear.

Jordan Spieth has it to 10-under through 14 holes to keep his dream of a third major this season alive.

Having already won the Masters and US Open this season, Spieth is gunning to become just the third player in history to win three of the four majors in one year, behind Ben Hogan and Tiger Woods.

Young Aussie Cameron Smith shot a two-under-70 to move to four-under for the tournament.