Jason Day has thrust himself into a tie for the lead midway through the third round of the opening US PGA tour playoff event at Ridgewood Country Club.

The Australian is three under on his round through 11 holes to push up to nine under for the week, tied at the top with American Kevin Chappell (seven holes).

Fellow Australian Adam Scott, the overnight co-leader, is just a shot behind after opening his third round with seven straight pars to remain eight under.

Americans Hunter Mahan (12 holes) and Cameron Tringale (seven holes) share third with Scott.

Day kickstarted his round with back-to-back birdies on the second and third holes, catapulting him into a share of the lead.

After a couple of solid pars while others surged ahead Day knocked in a 25-foot birdie putt on the sixth to once again join top spot.

While a bogey on the seventh was a minor setback when he drilled a 16-foot birdie putt into the hole on the 10th he was once again out in front.

World No.2 Scott has scared the cup with a handful of birdie tries but has yet to see anything drop.

Stuart Appleby continued to play solid golf, posting a 68 to move to six under and currently into a tie for 12th place.

With his spot in the playoffs next week on the line the Victorian has positioned himself to not only make week two, but also push towards the safe zone for week three.

Appleby split a birdie and bogey across his front nine but came home with a wet sail, making birdies on three of his last six holes.

Steven Bowditch shot 70 to be three under for the week while John Senden had a round to forget, his 74 dropping him towards the back of the pack at even par.

World No.1 Rory McIlroy earlier shot 70 to be four-under for the tournament.