Six players are tied for the lead at 6 under par as wet conditions Thursday led to a bevy of low scores during the first round of the Travelers Championship in Cromwell, Conn.

A trio of Americans -- Ryan Armour, Bronson Burgoon and Zack Sucher -- posted 64s on the par-70 TPC River Highlands course along with Mexico's Abraham Ancer, Canada's Mackenzie Hughes and South Korea's Kyoung-Hoon Lee.

Chez Reavie, fresh off a tie for third at the U.S. Open, continued his momentum with a 65. He is tied at 5 under with Keenan Bradley, Scott Langley, Brady Schnell, Robert Streb and England's Paul Casey.

Patrick Cantlay reached 6 under before the Memorial champion put his tee shot in the water on the par-3 No. 8 -- his 17th hole of the day. He finished in a pack of 12 players at 4 under that also includes England's Tommy Fleetwood, who is playing in the event for the first time.

Cantlay turned professional at the event in 2012, a year after carding a 10-under 60 at TPC River Highlands -- still the only 60 in PGA Tour history by an amateur. He led after 36 holes last year before finishing in a tie for 24th.

"I like coming back to places that I like playing golf at," Cantlay said. "I hit the ball really well today. One missed shot cost me two."

Another shot off the pace is Norway's Viktor Hovland, who is making his professional debut after a tie for 12th at Pebble Beach last Sunday. Hovland is tied at 3 under with Phil Mickelson, the only back-to-back champion (2001-02) in event history. Mickelson is in the field for the first time since 2003.

Defending champion Bubba Watson has won the event three times, but he managed only a 1-under 69 on Thursday and is in a tie for 61st. That's still two shots better than top-ranked Brooks Koepka, who continued his uninspired play outside of majors with a 1-over 71 that included four bogeys against three birdies.

Burgoon, 32, posted his first under-par opening round since March. Having missed the cut in 10 of his past 14 starts and currently 140th in the FedEx Cup standings, Burgoon needs a strong finish to the season to secure his Tour card for next season.

"My whole golf career has been an uphill battle, honestly," he said. "I feel like I've made golf a little more complicated than it should be. I'm trying to simply things and get my mind where I can compete.

"One thing I can do is compete."