Coughlin made two crucial birdies in the final four holes at Earl Grey Golf Club, holing one at the par-5 15th before playing the par-3 17th to perfection to shoot a one-under-par 71 and finish at 13-under 275.
She prevailed by two strokes over Japan’s Mao Saigo (69) while South Korea’s Haeran Ryu (75) slipped from a share of the lead late to tie for third at 10-under with her countrywoman Jenny Shin (67).
“I think I’ve had people believe in me for a really long time,” said 31-year-old Coughlin. “I wouldn’t be here without their push and their love. … It’s kind of indescribable, to be honest. I never really thought it would happen, but it did.”
Hannah Green was the leading Australian, posting a closing 74 to be tied 14th, nine shots behind the winner. Rookie Hira Naveed (73) was a shot further back, while Minjee Lee tied 37th at even-par with Sarah Kemp (72) a shot behind her and Robyn Choi (77) finished tied 59th.
Coughlin and Ryu were tied at 12-under at the 17th tee after Saigo bogeyed that hole in the group in front of them.
At the hockey-themed par-3 “rink hole,” a Canadian tradition featuring boisterous fans, Coughlin hit her tee shot to the front-left portion of the green. It rolled over a slope and stopped pin-high at the back hole location, leaving her a makeable birdie she was able to convert.
Ryu, meanwhile, carded a 4 at the hole, part of a bogey-bogey-bogey finish that dropped the 54-hole leader into her tie for third
Saigo made a run with five birdies on her card, including consecutive birdies at Nos. 9-10 and 14-15.
But the day belonged to Coughlin, who was one over on the day through 14 holes but kept relying on pars to stay in contention.
“I felt like I hung in there all day today,” said Coughlin, who led after the first and second rounds. “I didn’t really make anything. Just played super patient and stuck with it and they eventually went in.”
Jennifer Kupcho finished alone in fifth at eight-under following a final-round 71. Rose Zhang was in the mix but settled for a 73 and a tie for sixth at seven-under with Russia’s Nataliya Guseva (69).
