Adam Schenk carded a 10-under-par to surge into a share of the lead alongside top-ranked Jon Rahm and Justin Thomas at the halfway mark of the Farmers Insurance Open on Thursday.

Schenk, who is ranked 54th and has never won a PGA Tour title, carded a career-best PGA Tour round of 62, which included making 10 birdies and hitting four of 14 fairways.

The American, who turned 30 on Wednesday, made eight consecutive birdies was within one shot of equaling the course record, with his 15-feet putt on the 18th hole lipping out.

Reigning US Open winner Rahm, who opened the tournament with a six-under-par 66, backed up with a seven-under-round on the second day on the North Course at Torrey Pines.

World number six Thomas is locked with Schenk and Rahm at 13-under overall after his nine-under round.

The trio lead from Cameron Tringale at 12-under, with Peter Malnati next with 11-under.

Opening day leader Billy Horschel slipped down the leaderboard after a one-over round to be eight-under overall.

Will Zalatoris, who started and finished the second day with eagles, is among a group of six at seven-under including Dustin Johnson.

Phil Mickelson, Bryson DeChambeau, Jordan Spieth, Rickie Fowler, Tony Finau and Brooks Koepka were among the notable players to miss the cut.

Spieth's four-over card ended his run holding the longest active made-cut streak (20) on the PGA Tour.