Tony Finau birdied the final hole for an eight-under 62 on Saturday to share the lead with Rory McIlroy, coming into the final round of the Canadian Open.
Finau had the best round of the tournament so far, scoring an eagle on the par-five ninth before making four birdies on the back nine.
The 32-year-old is looking for only his third PGA Tour victory, with his last win coming in a playoff over Cameron Smith in last year's Northern Trust.
McIlroy had a tricky uphill putt to also birdie on the 18th hole, despite an exceptional approach to set it up, but he had to ultimately two-putt to finish the round after his birdie attempt skimmed over the edge of the cup.
The 33-year-old has been in confident touch at St. George's this week and continued that on Saturday, posting a five-under 65 with assertive driving and wedge-play.
After a bogey on the par-three eighth, the Northern Irishman responded with three birdies over the next four holes, before managing another birdie on the par-five 15th.
The final hole would have been an apt punctuation mark for his third round, after scores of 66 and 68 over the opening two days.
McIlroy has had to wait three years to defend his 2019 title, with the Covid-19 pandemic forcing a cancellation of the tournament in 2020 and 2021.
He is among five players ranked in the world's top ten in a high-profile field at Toronto, coming into next weekend's U.S. Open, with Justin Thomas and Sam Burns joined by Wyndham Clark and Alex Smalley on nine-under.
Cameron Smith has recovered from an opening-round six-over 76 to finish on one-under after 54 holes, posting a 68 on Saturday, while world number one Scottie Scheffler scored a disappointing 71.