American Spencer Levin remains on track for a maiden PGA Tour win after a three-under-par 68 moved him six shots clear at the Phoenix Open.

Levin rolled in four birdies and a bogey in his third round in Scottsdale, Arizona to move to 17 under for the tournament.

Compatriot and world number six Webb Simpson is in outright second on 11 under, one stroke ahead of Bubba Watson and Tour rookie John Huh.

Australia's Greg Chalmers is the only non-American inside the top ten and shares fifth place with four players on nine under.

It will take a momentous effort from anyone in the chasing pack to catch the 27-year-old Levin in Sunday's final round, with the Californian showing great poise at a sun-splashed TPC Scottsdale.

Levin recorded only his second bogey of the tournament at the par-five 15th after finding water off the tee, but responded with birdie at the difficult 17th, before closing out a solid round with par on the last.

Phil Mickelson, a two-time winner in Phoenix, carded five birdies in his 67 to move into a tie for 10th at eight under.

Bill Haas, last year's FedEx Cup winner, is a further stroke behind, while fellow Ryder Cup hopeful Ricky Fowler languishes in 60th place at four under.