The 2009 champion, back to his best after a series of injuries, won 6-3 6-1 7-6 (7-4) in one hour 56 minutes.

He will face Spain's Fernando Verdasco, who beat Britain's Andy Murray in round two, for a place in the last 16.

Another former champion Stan Wawrinka beat French qualifier Ugo Humbert 7-6 (7-5) 4-6 6-3 7-5 to advance.

The Swiss was unable to defend his 2016 title after undergoing two knee surgeries last year.

"My level is there. I'm playing really good tennis," said Wawrinka, who served for the match at 5-4 in the fourth only to be broken by the 20-year-old.

"I'm 33 years old, it's the first time after big surgery that I'm pushing myself that much, but in general, I think I did enough hard work to know and have confidence in my fitness.

"I think there is good chance that I'm playing better the next round than today, so I'm positive with that."

Wawrinka faces Milos Raonic next after the Canadian beat Gilles Simon 6-3 6-4 6-4.

Wimbledon finalist Kevin Anderson eased past France's Jeremy Chardy 6-2 6-4 6-4, while ninth seed Dominic Thiem survived a scare to beat American Steve Johnson 6-7 (5-7) 6-3 5-7 6-4 6-1.

However, Greek 15th seed Stefanos Tsitsipas - who came into the tournament in good form after reaching the Rogers Cup final this month - was beaten 6-4 6-3 4-6 6-3 by unseeded Russian Daniil Medvedev.

World number one and defending champion Rafael Nadal is in action later against Canada's Vasek Pospisil.