AP photo by Frank Franklin II / Mackenzie Hughes watches his tee shot from the third hole at TPC River Highlands during the first round of the PGA Tour's Travelers Championship on Thursday in Cromwell, Conn. Hughes shot a 60 for a three-stroke lead on a day when low scores were common.

CROMWELL, Conn. — Mackenzie Hughes did his part to help the PGA Tour switch its focus back to golf amid growing concerns about the coronavirus.

The 29-year-old Canadian shot a career-low 60 Thursday at the Travelers Championship, good enough for a three-shot lead over top-ranked Rory McIlroy, 10th-ranked Xander Schauffele and Viktor Hovland, who were tied for second after a day of low scoring at TPC River Highlands.

Hughes, whose only PGA Tour win came at the RSM Classic in November 2016, had a chance to shoot the 12th sub-60 round in PGA Tour history, but his 40-foot birdie attempt on his final hole came up short. Jim Furyk shot a 12-under 58 on the same course four years ago, the lowest score in a PGA Tour event.

Former Baylor School and University of Tennessee golfer Stephan Jaeger shot a 58 during the 2016 Ellie Mae Classic on the developmental circuit now known as the Korn Ferry Tour, six years after Ryo Ishikawa had the same score at a Japan Golf Tour event.

"I kind of joked walking off there that 59 wasn't even the record because of Jim's 58," Hughes said. "It's probably not even that special around here. But as a personal milestone, it would have been neat."

As it turned out, it was still good for a cushion — though not as big as might normally be expected.

Phil Mickelson, paired with McIlroy in his first competitive round since turning 50 years old, was one of six players to shoot a 64. Bryson DeChambeau's 65 was the worst score in the marquee threesome.

Tied with Mickelson for fifth were Tyler Duncan, Sergio Garcia, Louis Oosthuizen, Seung-Yul Noh and Michael Thompson.

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AP photo by Frank Franklin II / Phil Mickelson tees off from the third hole at TPC River Highlands during the first round of the PGA Tour's Travelers Championship on Thursday in Cromwell, Conn.

Baylor School graduates Keith Mitchell (69, tied for 79th) and Luke List (71, tied for 126th) will try to make it to the weekend in Connecticut after both missed the cut at last week's RBC Heritage tournament on Hilton Head Island in South Carolina.

There were 106 players who broke par Thursday. The record for a day at TPC River Highlands was set in 2011, when 111 players were 1 under or better in the second round.

Hughes' bogey-free performance included a 30-foot birdie putt on his penultimate hole, the par-3 eighth. Patrick Cantlay was the last to shoot 60 at the course, doing so as an amateur in 2011.

McIlroy, who also started on the back nine, eagled the par-5 13th and followed that up with two straight birdies. He made four more birdies on the front nine for a 31.

The four-time major champion from Northern Ireland played both of the first two events in the PGA Tour's return from a three-month shutdown during the pandemic, tying for 32nd at the Charles Schwab Challenge and sharing 41st at the RBC Heritage. Those tournaments were played without fans at the course in the interest of health and safety, and that stipulation didn't change this week.

"It's just been nice to get back into some competitive golf again," McIlroy said. "You know, it doesn't feel the same because you're not having thousands of people reacting to your birdies and getting that going. I felt the weekends have been a little flat for me just because that's when you're in contention and that's where you sort of start to feel it. Thursdays and Fridays don't feel that different to be honest, but into the weekends they do."

Mickelson learned earlier Thursday that he was granted an exemption into this year's U.S. Open for being in the top 70 in the world on March 15 after professional golf shut down. The 120th edition of the United States Golf Association event is set for Sept. 17-20 at Winged Foot Golf Club in Mamaroneck, New York.

A five-time major champion who is already in the World Golf Hall of Fame, Mickelson is a six-time runner-up at the U.S. Open, the only major he has not won.

"That worked out great, to be able to know that I have a chance to go back to Winged Foot and give it another shot," said Mickelson, who finished second there in 2006 after a double bogey on the 72nd hole. "But I've had 30 U.S. Opens. I've had plenty of opportunities, and so if I don't qualify, I want somebody else who deserves a spot, too, to play. As long as I'm playing well enough to compete to earn my way into the field, then I want to play and keep trying to win that tournament."

Hovland and Schauffele were the best among the afternoon wave Thursday. Schauffele was 8 under through 16 holes but missed a seven-footer for par on the 17th.

"The greens firmed up a little bit," he said. "The wind, just a little bit of wind can make any course hard, so in terms of hitting it really tight, it got a little trickier late in the day."

Hovland made a sloppy bogey on 17 but rebounded with a wedge to 4 feet on the par-4 18th for birdie.

Abraham Ancer, the runner-up to Webb Simpson this past Sunday, aced the 155-yard 16th. His 8-iron shot landed just over the pond guarding the green, with the ball rolling six feet and into the hole.

"It was very anticlimactic because there was nobody out there and we couldn't high-five or anything, but still, it was awesome to have my first PGA Tour ace," said Ancer, who finished off a 67 and was tied for 33rd.

The run-up to the tournament was consumed by news about the coronavirus and questions about how long the circuit can continue after two players — Nick Watney and Cameron Champ — and the caddies for Brooks Koepka and Graeme McDowell tested positive. Those were the only four positive tests of the 1,382 conducted by the tour since its return.

Players who test positive are required to withdraw. Koepka, his younger brother Chase, McDowell and Simpson withdrew because of concerns about the virus.

The withdrawals opened the door for alternates that included Tyler McCumber, who arrived Wednesday night from his home in Florida and shot a 65 to be part of the six-way tie for 11th. McCumber missed the cut at the Korn Ferry Tour event last week, then went camping for a few days in North Carolina's Pisgah Forest.

"I got back Tuesday, thinking that I had no chance of getting into the tournament," he said, "and then got the call from the tour about the option of possibly getting up here."