Charley Hoffman fired a 9-under 61 on Thursday to grab a 1-stroke lead after the opening round of the Travelers Championship.
Hoffman, who shared 45th last week at Merion, is looking for his third PGA Tour title. He shared second place at this event last year.
Hunter Mahan kept his strong play going. Coming off a share of fourth at the U.S. Open, Mahan carded an 8-under 62 and is alone in second place at TPC River Highlands.
Bubba Watson, who shared second last year with Mahan, is alone in third at minus-7.
Last year's U.S. Open winner Webb Simpson carded a 5-under 65 on Thursday. He was joined in fourth place by Rod Pampling, Zach Johnson, Graham DeLaet, Camilo Villegas and John Merrick.
Defending champion Marc Leishman is part of a group tied for 10th at minus-4.
Newly crowned U.S. Open champ Justin Rose is one shot back at 3-under 67.
"The announcement on the first tee today, being announced as the 2013 U.S. Open champion, I couldn't help but smile before I hit my first tee shot. That's an achievement that I've been dreaming about," Rose said. "I had a sluggish four or five holes where I struggled, but I stayed patient. I've stayed sort of committed to the same things that worked so well for me last week. That was my goal today, really."
Hoffman was in the first group out in the afternoon. He started with five pars in a row. At the sixth, he rolled in a 4-footer for birdie and made it two in a row with a 7-foot birdie putt at the seventh.
The 36-year-old Californian holed a shot from 169 yards out on the 10th for eagle. Hoffman rolled in a birdie effort at No. 12 and followed with a 19-foot eagle putt on the 13th to jump to 7-under.
Hoffman got up and down for birdie from a greenside bunker at the drivable 15th. That gave him a share of the lead. Hoffman closed with a 3-foot birdie effort at the last to end one ahead.
"It sort of crossed my mind, but not for long. I learned that 16, 17, 18 aren't an easy test," Hoffman said of shooting 59. "It's nice to come back after that finish last year."
Hoffman did all of that while playing with a broken tooth.
"The tooth broke at The Players this year. I haven't had time to go home. Got it re-plastered a couple times, so just going to get it re-glued. Nothing major, no pain or anything," Hoffman stated.
Mahan started with a 7-foot birdie effort at the 10th. After a pair of pars, he 2-putted for birdie at the 13th and followed with birdies on the next two holes.
The 2007 champion poured in a 23-footer for birdie at the 17th en route to making the turn at minus-5.
Mahan dropped his approach three feet from the hole at the second and he knocked that in for birdie. He holed a birdie effort from off the green at the fifth and followed with a 16-footer for birdie at the sixth. Mahan parred three in a row from the seventh to close out his round.
NOTES: Hoffman posted a 28 on the back nine for the best nine-hole score of his PGA Tour career and the best back nine since Vijay Singh shot 28 in 1998 ... Mahan's 62 was his fifth round of 63 or better at the TPC River Highlands ... Watson eagled the 15th for just his second eagle of the season ... Hoffman and Mahan had two of the 11 bogey-free rounds ... Rose set the best opening 36-hole score (126) here in 2010 ... Six of the top 10 from last week's U.S. Open final leaderboard are in the field this week -- Rose, Jason Dufner, Mahan, Nicolas Colsaerts, Gonzalo Fernandez-Castano and Rickie Fowler.