MONTREAL, Canada (AFP) — Canadian teenager Victoria Mboko took down top-seeded American Coco Gauff 6-1, 6-4 on Saturday, thrilling the home crowd as she reached the quarterfinals of the WTA 1000 tournament in Montreal.

The 18-year-old wild card saved all four break points she faced, and broke reigning French Open champion Gauff three times on the way to a comprehensive victory in just 62 minutes.

"I don't even know what to say still, I was kind of shocked about it all," said Mboko, adding that the support of the home crowd had buoyed her late in the second set.

"I just remember in the last game when I was up 5-4, the crowd kind of started cheering even louder, and everything got super noisy," she said.

"I kind of used that as more fuel for myself and to pump myself up a little bit more.”

"I think it helped me tremendously, especially in the last game, since they were so encouraging me. It was just amazing."

Mboko started the season ranked 333rd in the world and has worked her way up to 85 but the win over Gauff — who she took to three sets in Rome in May — is the biggest win of her career.

"Playing Coco is obviously never easy. She's number two in the world, and it has been such a great opportunity for me to play against someone like her," Mboko said.

"I was just happy I kept my composure today and I pulled it through."

Gauff, who had a combined 37 double faults as she struggled through her first two matches, was caught flat-footed as the Canadian teen raced through the first set in 25 minutes.

Gauff buckled down in the second, but she was unable to convert three break chances in the seventh game — coming up short on a drop shot and smacking a forehand into the net on the first two.

She gained another chance only to hit a service return long, then flew a volley wide to give Mboko a game point, duly converted when Gauff fired a forehand long.

Down 15-30 in the ninth game, Mboko leveled at 30-30 with a blistering backhand, then closed out the hold for a 5-4 lead.

Serving to stay in the match, Gauff fell in a quick 0-30 hole and double-faulted to give Mboko a match point, on which the American hit a backhand into the net.

"She played a really great match, that's basically it," Gauff said.

"I haven't played the best in this tournament, so I knew that it would be tough. I just felt like I could do better today, but I also knew that if I took my foot off the gas a little bit that she would take advantage of those moments, and she did."

Mboko will next play Spain's Jessica Bouzas Maneiro, who won a see-saw battle with China's Zhu Lin 7-5, 1-6, 6-2.

Former Wimbledon champion Elena Rybakina out-lasted Dayana Yastremska 5-7, 6-2, 7-5 to book a quarter-final clash with Marta Kostyuk.

Kazakhstan's Rybakina, the 2022 Wimbledon champion who won her first title in more than a year at Strasbourg in May, was slowed by nine double faults.

But she ultimately had enough to get past Ukraine's Yastremska, breaking her twice in the third set and sealing it on her fourth match point.

She'll face another Ukrainian in Kostyuk, who came from behind to beat American McCartney Kessler 5-7, 6-3, 6-3.