Patrick Sheehan saw Merion Golf Club for the very first time on Monday when he arrived for the 108th Pennsylvania Amateur Championship. Luckily, he knew someone with knowledge of the layout.

“I definitely tried to do as much research as I could,” he said. “My coach at school knows the course very well, so he kind of talked me through it and helped me through some of the holes.”

Sheehan was referring to Penn State men’s golf coach Greg Nye, the brother of long-time Merion head professional Scott Nye. The advice certainly helped Tuesday when the rising Nittany Lions junior fired the day’s best round, a 3-under-par 67, to take a 3-shot lead after 36 holes.

Sheehan, 20, a Talamore Country Club member from Doylestown, stood at 3-under 137 for his two trips around Merion’s famed East course. Jimmy Ellis of South Hills and Carlisle’s John Peters, an incoming freshman at Duke, were tied for second at 140. Ellis shot a 71 and Peters a 73.

Multiple Golf Association of Philadelphia major champion Jeff Osberg of Pine Valley, playing as a Pennsylvania Golf Association member, carded a 69 to tie Joshua Ryan (69) of the 1912 Club and Northampton’s Zach Juhasz (71) for fourth at 141.

Tanner Johnson of Nemacolin, the first-round leader with a 66, shot a 76 Tuesday to join a four-man group at 142.

Sheehan, who carded four birdies and one bogey, has struck the ball well the past two days, hitting 16 greens in each of his two rounds. He’s happy with the way he putted Tuesday over Merion’s fast greens, especially with his lag putting.

“I didn’t make some putts [Monday] but today I rolled some nice ones in,” he said. “I think my lag putting was the biggest thing that helped me because I had a good amount of long putts that I was able to get down in two. The greens were definitely a lot faster than yesterday.”

Peters got off to a rough start, going 3-over in his first five holes, but he played the remaining 13 in even par with two birdies and two bogeys.

“It’s just a day of patience, especially playing this golf course,” he said. “You can’t take what’s not yours. I felt like I made some mistakes out there but definitely did what I needed to do to keep myself in the tournament.”

Osberg birdied his first two holes and stayed steady, with only one bogey and a few key par saves, including a 6-foot putt at the par-3 third.

“I played great, putted really well,” he said. “I was hoping to get a few more birdies but I thought the course played extremely difficult, so obviously I thought 69 was a pretty good score today.”

A total of 40 players made the 36-hole cut of 8-over 148 for Wednesday’s final round.