SAN DIEGO — Davis Thompson capped a roller coaster of a back nine at Torrey Pines with a birdie to take the lead Friday in the Genesis Invitational. Scottie Scheffler had an unusually wild day off the tee and was right on his heels.

It set up for a compelling weekend in this $20 million signature event with two names leaping off the pages of the leaderboard — Scheffler, playing bogey-free despite hitting only five fairways, and Rory McIlroy showing the form that led him to victory at Pebble Beach two weeks ago.

Thompson made only two pars on the back nine and finished with a wedge to a foot for birdie and a 6-under 66, good for a one-shot lead over Scheffler.

“We’re halfway through, still a lot of golf left,” Thompson said. “Yeah, just trying to stay in my own lane.”

Scheffler, whose start to the year was delayed due to a hand injury, appears to be gaining comfort in his game even if it didn’t always look that way in far more agreeable weather along the Pacific bluffs.

He twice hit off the 12th tee. The first one was a 50-yard chip shot back to the 11th green for a remarkable par save after his tee shot on the par 3 was so far left that it twice bounced on the cart path before settling close enough to a water station that he got free relief.

He had a shot right of a bunker that was right of the fourth fairway and had to flex his right leg to keep from falling into the sand. He managed another par there. On the seventh, after another miss well to the left, he had to kick his right leg on the follow-through to muscle it out of rough. That found the green for a simple par.

He also holed a bunker shot for eagle on the par-5 sixth and converted three other birdies for a round of 67 that put him in the final group.

“I love seeing that,” Scheffler said about his ability to score on a day when his ball striking wasn’t quite up to standard. “I feel like those short little touchy shots are always the ones that are the last to come back after a longer layover. It’s nice to get those feels back.”

He then headed to the range for a quick session with his driver.

Thompson, who won for the first time last year at the John Deere Classic, was at 8-under 136 and will play in the final group Saturday with Scheffler.

Denny McCarthy birdied the last hole for a 70 and will be paired with McIlroy.

McIlroy surged up the leaderboard by going 5 under over his opening 10 holes until running into a few issues off the tee on holes where it’s hard to recover. He rallied with a pair of birdies, but his regret was playing the par 5s with only one birdie.

“I hit a lot of really good shots. I played well for the most part. I scrambled well,” said McIlroy, whose 67 left him only three shots behind. “I just didn’t take advantage of the par 5s. … Look, I made up for it in other places, which was nice. But I know going into the weekend I’m going to have to play the par 5s better.”

The signature events hosted by a player — Tiger Woods at the Genesis Invitational, though he is not playing this week — have a 36-hole cut of the top 50 and ties. Among those leaving early were Sepp Straka, who won in the California desert and was leading the FedEx Cup, and Jordan Spieth, who was coming off a tie for fourth in the Phoenix Open last week.

Also missing the cut was Max Homa, who has not made it to the weekend in the three events he has played this year with a 36-hole cut.

Scheffler wasn’t the only player who leaned hard on his short game. Thompson got up-and-down for par on the 10th hole. He chipped in for birdie on the next two holes, regained the lead with a birdie on the par-5 13th, and then bogeyed the next two holes.

But his 25-foot birdie putt on the par-3 16th got him back on track, and he had the advantage of being in the first cut on the 18th to help take some spin off a wedge he hit to tap-in range.

Among those chasing is Ludvig Åberg, who was eager to get back to Torrey Pines. He shot 66 to get within four shots of the lead on a meaty course that he loves. Aberg got a nasty stomach virus he tried to play through three weeks ago, and it caused him to withdraw at Pebble Beach after the opening round.

Aberg was at 140 with Patrick Rodgers, who had a 71.