Milos Raonic took advantage of only one of 16 break chances and still overcame Marinko Matosevic of Australia 7-6 (3), 4-6, 6-4 at the Thailand Open on Thursday.
After a first-round bye, the Canadian had to dig deep in a 2 1/2-hour match that featured lengthy baseline rallies.
"I created my opportunities, but I wasn't converting any," he said. "He was playing so well on a lot of break points, and a few I didn't play well. I just kept plugging away and finally broke him (in the third set)."
Gilles Simon of France, the 2009 champion and last year's runner-up, also reached the quarterfinals when he defeated Bernard Tomic of Australia 6-4, 7-5. The win was his 300th on the ATP tour, and sixth in a row following his title run in Metz last week.
"I feel confident on court, I was playing great tennis in Metz," Simon said. "Now I'm a bit tired and I have to be careful not to get injured because I just came back from injuries."
Also, Yen-hsun Lu of Taiwan ousted eighth-seeded Lukas Rosol of the Czech Republic 6-3, 6-2 to be the last Asian in the draw. Fifth-seeded Mikhail Youzhny of Russia also advanced to the quarters.