Fowler was making his first appearance in six years at The American Express to prepare for the next two weeks at Torrey Pines and TPC Scottsdale.

He's ahead of schedule, shooting an eight-under 64 on day two at PGA West's Jack Nicklaus Tournament Course for a share of the second-round lead with fellow American Scheffler at 15-under.

In position to make the trip over the hill to San Diego and Torrey Pines with his sixth PGA Tour title and first since Phoenix a year ago, Fowler set up shop last week at the nearby Madison Club after tying for fifth at Kapalua in the Sentry Tournament of Champions.

"It was nice to get a little work in, get some good practice and play out here in the desert to get used to being back in the desert," said Fowler, who grew up about an hour away in Murrieta.

"It's been very beneficial. I looked at that as something that was going to be the best opportunity for me to go into this West Coast swing to get the game where I want to and to play well."

He had opened with a 65 on Thursday (Friday AEDT).

Playing in the same third of the field as Fowler in the pro-am event, Scheffler also opened with rounds of 65 and 64.

Andrew Landry was a stroke out of the lead after a 64.

Sydney-born Davis shot a 67 following his opening round 66 to be the best-placed Australian at 11-under.

The 24-year-old is well ahead of fellow Australians in the field, who are led by Cameron Percy (four-under), Greg Chalmers and Aaron Baddeley (both three-under).

Tournament host Phil Mickelson needs a low round at the Stadium Course to make the cut after rounds of 70 and 72 in his first start of the year.

Australian Associated Press