Kurt Kitayama has continued to defy any doubters, holding off a stellar field to take a one-shot lead into the final round of the rich Arnold Palmer Invitational.

The 30-year-old Californian steadied himself down the stretch at tough and windy Bay Hill in Florida on Saturday, closing with two birdies over the last three holes to escape with an even-par 72 and stay at nine under.

Now comes the hard part for Kitayama, who is going after his first PGA Tour victory.

Defending champion and world No.2 Scottie Scheffler had five birdies over his last seven holes and finished with a 68 to be one shot behind Kitayama, along with Viktor Hovland of Norway (66), one shot clear of Tyrell Hatton (66).

The rest of the contenders are what is to be expected with a $US20 million event and every PGA Tour member from the top 50 in the world.

Rory McIlroy (68, six under), Jordan Spieth (74, five under), Justin Thomas (72, five under) and Max Homa (71, four under) all are within range of Kitayama if he were to lose ground or if Bay Hill is baked and brittle as it typically is for the final round.

Australia's Jason Day jumped 29 spots up the leaderboard to be tied 12th, six shots behind Kitayama after recording a 69 with six birdies and three bogeys.

Seeking to stay in the world top 50 at April 2 to secure a Masters invitation, world No.47 Day is well on track for that goal.

His countryman, 2013 Masters champion Adam Scott, went in the opposite direction, tumbling 22 spots to tied 31st at one under after a 75.

For now, Kitayama has held his own.

"Just proud of the way I fought," Kitayama said. "There's no giving up. It's just kind of in my nature. Even when it's going bad, you can't just like pack it in. You fight for every shot."

McIlroy made his move with his remarkable bogey-free 68.

"I think any time you can go bogey-free on the weekend at Bay Hill you're doing something right," McIlroy said. "I got myself right into the tournament, into the thick of things for tomorrow."

A three-time winner worldwide, Kitayama's search for that first PGA Tour title has been stopped by some of the game's best players - finishing second to Jon Rahm in the Mexico Open, Xander Schauffele in the Scottish Open, McIlroy at the CJ Cup in South Carolina.

Now he has to contend with a host of top players, and Scheffler is sure to get his attention. Scheffler already has successfully defended one title this year at the WM Phoenix Open.

Meanwhile, Jon Rahm is in danger of losing the world No.1 ranking. He opened with a 65 and followed with two straight 76s. He made five straight bogeys around the turn in the third round.

with AAP