Ryan Armour ended the opening round in a six-way tie for the lead at the Travelers Championship on Thursday.

Armour carded a six-under-par 64 to be level and a stroke clear alongside Bronson Burgoon, Lee Kyoung-hoon, Abraham Ancer, Mackenzie Hughes and Zack Sucher at TPC River Highlands.

Armour, who has just one PGA Tour win after turning professional in 1999, tied his low round of the season after a closing birdie on the par-four 18, while Hughes joined the pack in control after a clutch birdie putt on his final hole.

Paul Casey closed the first round a shot adrift and he was joined by Chez Reavie, Keegan Bradley, Robert Streb, Scott Langley and Brady Schnell in Cromwell, Connecticut.

Casey – one of the runners-up – had a share of the lead until a bogey on the par-four 18 dropped him down a peg. 

The Englishman, who is chasing his second win of the season, was bogey-free up to that point and was just a couple of feet away from an ace on the par-three 11th hole.

Defending champion Bubba Watson shot a one-under-69 to be five behind the leaders.

Viktor Hovland and Matthew Wolff, meanwhile, made their professional debuts on Thursday.

Hovland broke Jack Nicklaus' record for the lowest 72-hole score by an amateur at the U.S. Open and the Norwegian backed that up with a first-round 67.

American Wolff – a former team-mate of Hovland at Oklahoma City University – posted an even-par 70 in his pro bow.