Brooks Koepka delivered one of his best rounds since returning to the PGA Tour, firing eight birdies and two bogeys for a six-under 64 to grab a share of the first-round lead at the RBC Canadian Open in Toronto. His putting sparked late, he said, after a strong ball-striking stretch over the previous six months.

Shane Lowry sits one stroke behind after a five-under 67, though the Irishman will rue his back-nine performance. He carded four birdies on the front side but managed just one on the back, salvaging his round with a closing birdie. England's David Skinns surprised at five-under 65, while countrymen Tommy Fleetwood and Matt Fitzpatrick posted three-under 67s.

Several players joined Koepka atop the leaderboard at six-under, including Americans Sahith Theegala, Eric Cole and Sam Burns, Canada's Matthew Anderson, and Argentina's Emiliano Grillo. Meanwhile, 2023 champion Nick Taylor recovered from a bogey on 17th to remain in contention at three-under.

Aaron Rai, fresh off his PGA Championship win, struggled to a one-under 69 with three bogeys, while Alex Fitzpatrick's double-bogey at the second hole derailed his two-under effort. The crowded leaderboard sets up an intriguing second round.