American Patrick Rodgers continues to lead from Daniel Berger and Scott Stallings who posted 63 and 64 respectively on Saturday.
Appleby was one of three golfers to shoot 7-under on day three, his eight birdie-one bogey effort jumping him 37 places up the leaderboard to T18.
The nine time PGA Tour winner has limited playing status in 2017 and has struggled all year with nine cuts missed and two withdrawals in 14 starts though clearly found something ahead of the third round.
He missed just one fairway and three greens on the day, his lone bogey coming after finding a greenside bunker at the 18th, his ninth hole of the day.
Appleby wasn’t the only Australian to go low on day three, Cameron Percy posting a 5-under 66 to move 19 places up the standings to T27.
Low scoring was the order of the day in Illinois with Berger one of three players to shoot 8-under 63 to set up a thrilling Sunday shootout.
17 players will begin the final round within five strokes of the lead with both the title, and a berth in next week’s Open Championship, up for grabs.
Rodgers’ lead is two over Berger and Stallings with Bryson DeChambeau and another American, Nicholas Lindheim, sharing fourth a stroke further back.
Appleby and South African Rory Sabbatini are the only non-Americans in the top 25 with one round to play, Rodgers, Stallings, Lindheim and DeChambeau in the drivers’ seat to claim the Open spot at Royal Birkdale.
Rodgers added a third round 68 to opening scores of 65-64 to move to 16-under and in good position to claim a maiden PGA Tour title.
Greg Chalmers was the last of the Australians to make the cut and is T44 after a third round 69.