Australia’s former World No.1 will go into Sunday in outright second place, just one shot behind leader Justin Thomas, at the rain-affected Genesis Open at Riviera Country Club in Los Angeles.

The pair are playing in the final group and must return to finish the 3rd hole of their third round before playing a further 33 holes.

The 38-year-old Scott has more US Tour wins (13) to his name than 25-year-old Thomas (nine) but he hasn't triumphed since March, 2016.

His ranking is No.33 while Thomas is World No.4.

Big-hitting Thomas is a prolific front runner.

But Scott, who won the 2005 event at Riviera when it was shortened to 54 holes due to severe rain, has made just one bogey in 38 holes this week.

The Queenslander ranks first in the field for scrambling and fifth for strokes gained in putting.

"I've managed to scramble well this week and I'm going to have to do that all day tomorrow," Scott said.

"If I can have some good (play) in between, it will go a long way.

RIGHT: Thomas leads the Genesis Open by one shot at Riviera Country Club. PHOTO: Harry How/Getty Images.

"It's a big day; a lot of golf. It's a great day to get your rhythm early and make a move."

Scott will resume at 12-under par, one shot ahead of third-placed Americans Patrick Rogers and JB Holmes, who is also in the final group.

Scott and Thomas were tied at 11 under after two rounds but Thomas took sole possession of the lead with an eagle at the par-5 1st hole when they returned to resume play late on Saturday.

"I hope so," Scott said when asked if the overnight wait to resume the third round could hurt Thomas's momentum.

"The main thing was not to make any errors; the worst thing I could have done is bogey (the 2nd hole) when he made eagle (on the 1st) and then wait (12 hours), so I'm happy with what I did out there."

Event host Tiger Woods had crowds roaring with a huge move on Saturday.

The 14-time major winner reeled off three birdies and an eagle in his first four holes of the third round before three pars left him at six under.

Woods will resume the third round on his 8th hole, the par-5 17th, on Sunday.

Victorian Marc Leishman is tied with Woods at six under, while Aaron Baddeley (two under) and Cameron Smith (one under) round out the Australian contingent who made the 36-hole cut.

- Evin Priest, Australian Associated Press