San Francisco Frontiers - Rublev, Tiafoe sweat out three-set wins in Toronto

Sixth seed Rublev, runner-up in Canada a year ago to Alexei Popyrin, advanced 5-7, 6-4, 6-3 as Lorenzo Sonego double-faulted on match point in their contest after two and a half hours.

Tiafoe, the number seven, confessed to a bad day but earned his win the hard way as he beat Australian Aleksandar Vukic 6-3, 4-6, 6-3.

"The ball was flying a lot, it was really ugly, but I'm happy to get through it," Tiafoe said.

"It doesn't matter how you win. You just have to compete. It was up and down for me today."

Rublev's victory extended the loss streak against the top 20 which has been plaguing Sonego for more than a year.

The Italian has dropped his last 16 matches against the elite dating to Roland Garros last season. He now stands 2-3 against Rublev.

The seed finished with 29 winners while Sonego had 41 unforced errors.

Rublev, who won his 25th match of the season, now goes against Alejandro Davidovich Fokina, who beat him this season on clay in Barcelona. The Spaniard earned his spot 6-2, 6-4 over Jakob Mensik.

"I'm really happy, it's my first time in the round of 16 here in Toronto," Rublev said of the event, which alternates each season with Montreal.

"I'm excited, motivated and happy with my performance."

The winner said he had to adjust his serve in windy conditions as he made his comeback after losing the opening set.

"I played more aggressive in the second set and made fewer mistakes. I was doing more with my serve. I had to slow it wide in the wind."

Tiafoe next lines up against another Aussie in Alex de Minaur, who advanced when compatriot Christopher O'Connell pulled out with an injury.

Tiafoe earned his 22nd match win of the season as he swept the final three games against Vukic, who had lost 15 or his previous 18 matches prior to arriving in Canada this week.

"I had chances in the second set -- I could have gotten out in straights (sets)," Tiafoe said. "But he fended them off and made me play a third."

The American, a quarter-finalist last week in his Washington hometown, will be playing for the second time in a Masters fourth round this season after Madrid in the spring.

Second seed Taylor Fritz was bidding for the last 16 later as he faced a third-round test against Canadian Gabriel Diallo.

Czech Jiri Lehecka completed a 3-6, 6-3, 6-4 fightback to overhaul Arthur Fils as the Frenchman played for the first time since Roland Garros due to a back injury.

K.Hernandez--SFF