NEW YORK -- Eugenie Bouchard is salvaging an otherwise forgettable season at the U.S Open.

The 25th-seeded Canadian has advanced to the fourth round of the last Grand Slam of the season after defeating Slovakia's Dominika Cibulkova 7-6 (9), 4-6, 6-3.

Bouchard fired six aces in the back-and-forth match, and broke Cibulkova four times on 11 opportunities.

The native of Westmount, Que., saved 12 of 16 break points against.

Bouchard is starting to look like her old self at Flushing Meadows. She had lost 13 of 16 matches in WTA and Fed Cup play heading into the U.S. Open.

That's in stark contrast to her 2014 season, when she made the Wimbledon final and the semifinals at the Australian Open and French Open.

Next up for Bouchard is Italy's Roberta Vinci, who beat the Canadian 6-1, 6-0 in the second round of a U.S. Open tuneup in New Haven, Conn., last week.

Also Friday, Milos Raonic of Thornhill, Ont., lost to Spain's Feliciano Lopez 6-2, 7-6, 6-3 in men's third-round action.

Raonic struggled with back pain throughout the Grand Slam tournament, requiring attention from a physiotherapist repeatedly during the match with Lopez.

"My tennis is in OK shape as long as I can get my body behind it," Raonic said. "I was able to win two pretty good matches, considering some sort of setback. But I got to just try to get to 100 per cent, and hopefully I can play a lot more matches where it's just my tennis is the only thing I'm worrying about."

Known for his big serve, Raonic was limited to 12 aces compared to Lopez's 16. Raonic also made 40 unforced errors versus Lopez's 22.

"It's not enjoyable. It's not fun," Raonic said. "Just try to make the most of some situations and deal with it as much as you can.

"Obviously what I had in my capacity wasn't enough today."

Later Friday, Bouchard and mixed doubles partner Nick Kyrgios defeated Elina Svitolina and Artem Sitak in first-round play.