LA JOLLA, Calif. — If someone is going to stop Justin Rose this weekend at Torrey Pines, it’s going to take some seriously good golf to do it.

Two rounds into the Farmers Insurance Open, Rose is 15-under after shooting 66 Friday on the South Course, a sterling round that followed his 63 on Thursday on the North Course.

Rose, who tied the 36-hole record for the tournament, is trailed by Hideki Matsuyama at 12-under following a 66 Friday on the South. Billy Horschel, Ryan Palmer and first-round leader Jon Rahm are all 10-under.

Rahm followed his first-round 62 on the North Course with a disappointing 72 on the South, which has played two shots more difficult.

Rose, ranked No. 1 in the world, has not had a problem with either course.

“It was a great day out there,’’ Rose said. “You never quite know what to expect on the South Course. The job was done today. That was really nice to go out there and play a positive round. I can build on that for the weekend.

“I won’t get ahead of myself right now. We’re at the halfway stage. Going into [Saturday], I should know what to expect. It’s a tough test, that South course, and I think 66 is apparently the joint low score for the two days. Anytime you equal that, you know you’ve gone out there and you’ve put a good round together.”

Horschel, who was paired with Rose the past two days, said: “I’ve got to hit the ball like he did the last two days [to have a chance to win]. He’s absolutely flagging it and swinging it really well.”