AP photo by Denis Poroy / Adam Schenk holds up his golf ball after finishing his round on Torrey Pines' North Course at the Farmers Insurance Open on Thursday in San Diego. Schenk shot a 62 and shared the lead with Jon Rahm and Justin Thomas.

SAN DIEGO — Top-ranked Jon Rahm and No. 6 Justin Thomas made the birdies they needed to keep pace on the easier North Course at Torrey Pines on Thursday, and they shared the lead with hard-charging Adam Schenk after two rounds of the Farmers Insurance Open.

Schenk, also playing the North Course, made eight straight birdies to shoot a 10-under-par 62 — his career low on the PGA Tour — as he joined Rahm (65) and Thomas (63) at 13-under 131 through 36 holes.

The 30-year-old Schenk, who grew up on an Indiana sod farm and played college golf at Purdue, started his impressive run of birdies on the fourth hole and ended it on No. 11. He also birdied Nos. 16 and 17 in his bogey-free round as he made a bid for a breakthrough win.

In contrast to the 27-year-old Rahm, the Spanish star with six PGA Tour wins, and the 28-year-old Thomas, whose 14 victories include the 2017 PGA Championship, Schenk is No. 165 in the Official World Golf Ranking.

All three leaders opened Wednesday on the South Course, where Rahm won the U.S. Open last year for his first major. Rahm also got his first PGA Tour victory in 2017 at Torrey Pines, a municipal facility on the bluffs overlooking the Pacific Ocean. The final two rounds will be played Friday and Saturday on the South Course.

Cameron Tringale (65 North) was one shot behind the leaders, with Peter Malnati (66 North) alone in fifth at 11 under.

Baylor School graduate Luke List (68 North) was near the top for the second straight day, one of five players tied for sixth at 9 under. The cut was at 3 under, and two other former Red Raiders standouts in the field missed it — Stephan Jaeger (77 South) by one stroke and Keith Mitchell (71 North) by four.

Schenk recorded the longest consecutive birdies streak at this tournament since 2003.

"I lost track of how many I made in a row, but there was a lot of low scores on the North Course yesterday, and I knew there was a lot of gettable holes and I needed to keep going if I wanted to get up on top of the leaderboard and hopefully stay there throughout the weekend," Schenk said. "So I know I had to try to keep the pedal down and not get satisfied with how many birdies I made."

Schenk struggled to hit fairways, but his approaches were good enough to give himself reasonable birdie chances.

"Just a lot of long putts," he said. "It's not like I was hitting it to 10 feet every time making the putts. I had a lot of lengthy ones."

Rahm closed his opening round Wednesday with an eagle for the best score of the day on the South Course. He birdied five of his first eight holes on the North on Thursday before making his only bogey.

"I mean, it wasn't bad yesterday, it certainly wasn't bad today," Rahm said. "I managed really well today, and it feels good because if you tell me before the round I'm going to hit four fairways and shoot 7 under, I'd tell you that something out there must have been really good, which today was. For how little fairways I hit, I was able to hit a lot of those greens from the rough, which is not the easiest thing to do."

Thomas, playing the Farmers Insurance Open for the first time since 2015, had nine birdies in his bogey-free round.

"I played well, I drove it well, something you've got to do out here on the North Course," he said. "I mean, both courses, but if you drive it well, you've got a lot of wedges, a lot of short holes, four par-5s. Made some nice putts when I needed to, just kind of some of those short mid-rangers, and it was a solid day."

Billy Horschel, who opened with a 63 on the North, struggled through a 1-over 73 on the South — he made a double bogey on No. 14 — and dropped five shots off the lead into a tie for 12th.

The featured afternoon threesome of Bryson DeChambeau (72), Rickie Fowler (76) and Jordan Spieth (78) played the South and all missed the cut, with the big-hitting DeChambeau grabbing at his lower back in apparent pain on several occasions.