(Photo credit: Raymond Carlin III-Imagn Images)

Brooks Koepka is one of six players tied atop the leaderboard after one round of the RBC Canadian Open on Thursday in Caledon, Ontario.

The five-time major winner shot a 6-under-par 64 at TPC Toronto at Osprey Valley's North course. Koepka matched Sahith Theegala, Eric Cole, Sam Burn and Argentina's Emiliano Grillo, and by the end of the day, Canada native Matthew Anderson made it six at 6 under.

By day's end, 12 players formed a logjam at 5-under 65, one behind the leaders. The group included Canadian Adam Svensson, Irishman Shane Lowry and Tony Finau, who is aiming to turn around a disappointing season and qualify for next month's Open Championship.

As for Koepka, he has been back on the PGA Tour since January after more than three years away with LIV Golf. He's placed in the top 20 in six events this year, but a win this weekend would be his first in a standard PGA Tour event since the 2021 WM Phoenix Open.

'It's just a matter of going out and playing golf. I think I've gotten more comfortable as the weeks have gone on,' Koepka said. '... We've got a big one next week (the U.S. Open), so the game better be sharp.'

Koepka shot a 5-under 30 on the back nine with three sets of consecutive birdies, including Nos. 17-18, against one bogey. He was among the leaders in the field in putting, having made a 17 1/2-footer for birdie at the par-4 ninth hole and a 19-foot birdie at the par-3 14th.

'I've played great this year. Like I said, it's just the putting that's held me back and trying to be mechanical, trying to be maybe too much in the stroke and figure everything out,' Koepka said. 'But it was nice today to at least kind of turn the brain off and go from there.'

Of the other co-leaders, Grillo is enjoying a particularly stellar week. At nearby Lambton Golf and Country Club on Monday, Grillo earned medalist honors after 36 holes of U.S. Open qualifying. He carried that form into Thursday and birdied five of his first eight holes.

'I putted well on the front nine and not a lot of action on the back nine,' Grillo said. 'I was able to make some good saves and a great drive on 18. I was somehow able to miss the green from 160 yards. I was able to make 4. Yeah, good overall. Played from the fairway, which is kind of important out here.'

Anderson, who plays on the Korn Ferry Tour, is the surprise low Canadian after one round. Of the six co-leaders, he was the only player to stay bogey-free. The Mississauga, Ontario native said his parents and some other family and friends are on hand to support him this week.

'It was a long day,' Anderson said. 'I'm going to get a good sleep. I'm going to just try my best to take it one shot at a time just like I did today and full send on every shot like I try and do. As long as we do that, I'll be happy with whatever happens.'

Other Canadians in the mix include Taylor Pendrith (4-under 66) and Nick Taylor (3-under 67). Taylor was the first Canadian since 1954 to win his national open when he sank a 72-foot eagle putt to win a playoff in 2023.

England's Tommy Fleetwood, who was on the wrong side of that playoff, opened Thursday with a 3-under 67, as did countryman Matt Fitzpatrick.

The top three finishers in Canada not otherwise exempt will qualify for the Open at Royal Birkdale. Finau has yet to play in a major this year and failed to qualify for the U.S. Open; he's well aware a high finish this week could do the job.

'I feel really close,' Finau said of his game. 'I was just talking to my son last night about it. And he always asks me how I'm feeling before a tournament, and I told him, I said, 'I'm driving it as good as I have all year, my iron play is starting to come around and the putter's felt good over the last five, six weeks.' I feel like it's all starting to come around, you just never know when it's going to click. But this was a good start to hopefully a good week.'

--Field Level Media