World number four Jon Rahm, chasing his second US PGA Tour title in as many weeks, shares the lead with rookie Davis Thompson heading into the final round of the American Express Tournament.

Fourth-ranked Spaniard Rahm sounded supremely confident after firing an eagle and six birdies on Saturday in a seven-under par 65 to pull level with overnight leader Thompson on 23-under 193 at La Quinta, California.

Thompson, a former amateur standout at the University of Georgia and a winner on the Korn Ferry developmental tour, carded a five-under par 67 to keep himself squarely in the hunt for a first PGA Tour title.

"Nothing but positive. That's all I can say," said former US Open champion Rahm, who won this title in 2018.

"Ball striking felt amazing. Hit a lot of great shots out there off the tee. Giving myself a lot of opportunities with the irons. Took advantage of quite a few of them."

Even some difficulties on the greens coming in -- most notably a three-putt bogey at the par-three 17th -- didn't dampen Rahm's confidence, although he said he knew another low score would be needed on the Stadium Course, where the final round will be held after the first three rounds were spread over three courses.

Rahm, who opened 2023 with a come-from-behind victory in the Tournament of Champions in Hawaii this month, walked off the 18th with the lead, even though he couldn't get a 12-foot birdie putt to drop at the last.

He had expected Thompson, who piled up a US tour record-equalling five eagles over the first two rounds -- to regain the top spot.

But the 23-year-old American, who had five birdies in his first 12 holes but dropped out of a tie for the lead with a bogey at the 14th, found only one more birdie coming in -- rolling in a four-footer at the 16th at the Stadium Course.

"I was really proud with how I stayed patient," Thompson said. "I didn't really force anything. Made a bad bogey on 14, but came back and birdied 16, so it was a good way to finish."

- Aggressive mindset -

Thompson acknowledged he was still getting used to the three-course format, which requires studying more courses and has the cut come after 54 holes.

"It's definitely different," he said. "I just try to have an aggressive mindset and try to go hit some good shots."

Thompson said he was looking forward to going up against Rahm, testing the nerves he has already honed in junior golf, amateurs and on the Korn Ferry Tour.

"Now it's on one of the biggest stages," he said.

The leading duo were four strokes clear of J.T. Poston and South African Christian Bezuidenhout. Bezuidenhout had 10 birdies in his 10-under 62 and Poston carded a six-under 66 to join him on 197.

Another four players shared fifth on 198. That included American Harry Higgs, who had 12 birdies and a double-bogey in his 62 on the Nicklaus Tournament course.

Second-ranked Masters champion Scottie Scheffler, who could finish as low as solo ninth and still supplant Rory McIlroy atop the world rankings, carded a six-under par 66 that left him tied for tied for ninth on 17-under 199.

American Dylan Wu joined the group of six on 199 with an 11-under par 61 that featured 11 birdies on the Nicklaus course.