Brooks Koepka made the RBC Canadian Open feel a lot more dangerous Thursday.

Round 1 at TPC Toronto turned into a birdie sprint after morning rain softened the course and gave players the green light to attack. Koepka and Sam Burns headlined a six-way tie for the lead at 6-under, with Emiliano Grillo, Sahith Theegala, Eric Cole and Canadian Matthew Anderson also opening with 64s.

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The low scoring wasn’t a fluke. The field scoring average was 68.5, a number that showed just how playable TPC Toronto became once the fairways softened and the greens started accepting aggressive approaches. Ninety-seven players in the 147-man field broke par, turning Friday’s second round into an early pressure test for anyone trying to separate.

Koepka’s finish was the loudest part of the day. He made four birdies over his final five holes and looked especially comfortable late, a notable development for a player who has said the putter has held him back at times this season. His power was still there, too, as he averaged 332 yards off the tee and gained strokes on approach.

That combination is why Koepka is already getting serious attention entering Round 2.

“I don’t think the ball striking was as good as it’s been as of late,” Koepka said after his 64, “but it was nice to see the putter finally heat up.”

Burns may have the betting market’s attention even more. FanDuel listed him as the RBC Canadian Open favorite at +500 after Round 1, while Koepka sat at +950. Eric Cole followed at +1300, with Theegala at +1500. Tommy Fleetwood, Matt Fitzpatrick and Shane Lowry were all at +1600.

Burns has good history at this event, and his opening 64 reinforced that he’s carrying strong form into another massive stretch of the season. He had a chance to take the outright lead late but settled for birdie at the par-5 18th.

Cole also has extra motivation. He entered the week ranked No. 63 in the Official World Golf Ranking, with the top 60 after this event earning U.S. Open exemptions.

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Another name to watch is Jackson Suber, who opened with a 4-under 66 despite losing ground with the putter. Suber ranked near the top of the field tee-to-green, and if the putter rebounds, he’s positioned to chase a top-20 finish.

The leaderboard is packed, but Koepka’s name changes the temperature.

When he’s driving it long, attacking pins and finally making putts, the RBC Canadian Open suddenly has a heavyweight problem.