Im Sung-jae sits one shot off lead at The Open; Kim Si-woo tied for 13th

Im Sung-jae sits tied for second, one shot off the lead, at the 154th The Open Championship, the final men's major of the season, which carries a purse of $17.75 million.

Im carded a 4-under-par 66 — five birdies against one bogey — in the first round Thursday at Royal Birkdale Golf Club (par 70, 7,223 yards) in Southport, Merseyside, England, to share second place with Daniel Brown of England. American Jackson Suber leads by one.

Suber, playing a links course for the first time, fired a 5-under 65 with one eagle, six birdies and three bogeys to claim a surprise lead. He earned his spot in the field by finishing tied for fourth at the RBC Canadian Open, and credited his strong opening round to switching his driver and golf ball.

Bryson DeChambeau of the United States posted a 3-under 67 to join Thomas Detry of Belgium, Francesco Molinari of Italy, Robert MacIntyre of Scotland and Alex Smalley of the United States in a tie for fourth.

Im warmed up through the front nine with a birdie and a bogey apiece, then turned on the precision iron play on the back nine to collect four birdies without a dropped shot.

He drained birdie putts of 1.5 meters and 6 meters on the 10th and 11th holes, then added birdies on the par-5 14th and 17th. On the 14th, he stuck his third shot to within 80 centimeters of the pin; on the 17th, he holed a 3.5-meter birdie putt.

"There wasn't much wind today," Im said in his post-round interview. "I didn't have much trouble with my tee shots or second shots. I memorized my tee shots and layups during the practice rounds and stuck to my routine, which helped. I didn't force anything, and the putts dropped when I had chances — that's how I got to 4 under."

Im added that the course suited his game from the start of the week. "I'd say this is the tightest Open course I've played so far," he said. "There are holes where you have to lay up with something other than a driver because of where the bunkers are. Once the club selection is set, there's no risk and you feel comfortable. If you keep it in the fairway, it doesn't play that hard. That suits me."

Kim Si-woo opened with a 2-under 68 — three birdies, one bogey — to share 13th place with defending champion Scottie Scheffler of the United States. "I started a bit shakily early on but finished well," Kim said. "My putting was better than I expected. My goal is to make the cut. I'll play smart, and if I can be aggressive on the back nine when the situation calls for it, that would be great."

Scheffler briefly held the lead after making four birdies through the sixth hole, but two bogeys on the remaining holes dropped him down the leaderboard. "I felt like I could have done a bit better, which is a little disappointing," he said. "But if I keep the ball-striking going like I did today, I think I can have a good week."

Kim Joo-hyung, who won the Genesis Scottish Open last week, traded two birdies and two bogeys to finish at even par, placing him tied for 41st.

"It's a major, so the course is always going to be tough," Kim said. "The wind picked up in the afternoon. Overall I played reasonably well and didn't feel too stressed. A few more birdies would have been nice, but it's not a bad start."

Ham Jeong-woo and Yang Ji-ho found the step up in class a sobering experience. Both carded 7-over 77s to sit tied for 146th and face a serious cut threat. "I wish I had played better — it was just so hard," Ham said. "I thought it would be difficult, and it really was. I've never played a course like this."

Title contender Rory McIlroy of Northern Ireland struggled to a 2-over 72, joining Matt Fitzpatrick of England and Hideki Matsuyama of Japan in a tie for 86th, leaving him with cut concerns of his own.