July 23 (UPI) -- Richy Werenski made a short birdie putt on his final hole for an 8-under 63 to take a one-shot lead in Thursday's opening round of the 3M Open at TPC Twin Cities in Blaine, Minn.
The 24-year-old Werenski, who is winless on the PGA Tour, broke a tie with Michael Thompson after his ninth and final birdie on hole No. 18. He recorded a bogey on the par-5 third but otherwise took advantage of the soft greens.
"I have a good feeling they'll get nice and firm as the week goes on, but you start it online, it will stay there. They're really good," Werenski said. "... To play a round like I did today, you've got to make the putts, but ... I feel like my irons have really been coming along."
Thompson, who enjoyed a bogey-free round, finished one shot back of Werenski due in large part to the accuracy of his putting. Thompson entered the week in 151st place in the FedEx Cup standings.
"It's really just being diligent about playing my own game," Thompson said. "I'm not the longest hitter out here. I'm a really good putter, so I'm going to rely on that."
Meanwhile, Dustin Johnson -- the fourth-ranked player in the world -- withdrew from the tournament because of a back injury after his opening-round 78.
Johnson, who won the Travelers Championship last month, posted back-to-back 80s last week at the Memorial Tournament for the highest 36-hole score of his pro career.
"Kind of the same last week," he said. "I just struggled with my iron play, and that makes it difficult."