SAN JOSE, Calif. - Canada's Milos Raonic opened his defence of the SAP Open with a 6-2, 7-6 (7) win over Germany's Tobias Kamke on Wednesday.

Raonic, the third seed at the tournament, had his big serve on display, as the rising star from Thornhill, Ont., fired 18 aces past his opponent.

Raonic, who had a bye in the first round, got off to a roaring start, taking just 30 minutes to win the opening set while firing seven aces past Kamke.

The second set was a different story, as Raonic had to constantly play catchup with Kamke, forcing a tiebreaker by holding serve in the 12th game.

Kamke seemed poised to send the match to a third set when he took a 5-1 lead in the tiebreaker. But Raonic fought back to make it 5-3, then took the lead with consecutive aces.

Kamke scored the next two points to go up 7-6, but Raonic took the next three points, finishing the straight sets win by breaking Kamke's serve.

Raonic will face the winner of the second-round match between sixth seed Kevin Anderson of South Africa and Matthew Ebden of Australia in the quarter-finals on Friday.

Second seed Andy Roddick overcame a right ankle injury and a troublesome right hamstring, rallying past Ukrainian-born American Denis Kudla 6-7 (5), 7-6 (5), 6-4.

Almost a month since he retired in the second round of the Australian Open with a slight tear in his hamstring, Roddick injured his ankle running to his right late in the second set. He crumbled to the floor, pulled his hands over his hat and let out a painful roar that echoed around the arena.

Roddick regrouped with a brace around his hamstring, won the second-set tiebreaker after Kudla double-faulted and came back from 2-0 down in the final set for the victory.

"The best thing I did was just exist out there," Roddick said.

Roddick's return to the court had more drama than he could've imagined.

The bold and brash American complained of the flashing video board that hangs from the arena's rafters, stopped play more than once while flashbulbs on fans' cameras or phones popped, squeaked his shoes between points on the indoor surface and had his share of words with line judges -- even shaking his head and walking off after a video replay didn't go his way.

All those worries faded late in the second set.

Running to his right along the baseline to chase down a ball while up 5-4, Roddick pulled up limp. He dropped to the ground and the arena fell silent for several seconds until his agonizing grunts.

After a brief medical timeout, Roddick rallied in impressive fashion.

Roddick still had more of a plodding than polished pace -- which showed even before the ankle injury -- but his hard-hitting serve found the lines and so did his passing shots. He put the pressure back on the go-for-broke Kudla, who sailed a serve wide for a double fault and then another passing shot out to hand Roddick the final two points of the second-set tiebreaker.

Even then, Kudla controlled the pace.

Both players held serve until Kudla broke Roddick to go ahead 2-0 in the final set. Roddick immediately broke back, and followed with a series of slices and spins to stay along the baseline to break again at 4-3.

Roddick held on to advance to the third round. He'll get an extra day of rest and won't play again until Friday, facing the winner of the Denis Istomin-Michael Russell match.

Roddick, who had a first-round bye, partially tore a tendon in his hamstring against Lleyton Hewitt on Jan. 19. He was injured in the second set against Hewitt, played 16 more games before retiring and has only practiced sparingly since.

This time, he survived.

And the rest of the field suddenly looks a lot less daunting.

Earlier in the day, top-seed Gael Monfils of France withdrew with right knee inflammation. He also plans to withdraw from next week's ATP Tour stop in Memphis.

Ryan Harrison advanced to the second round by upsetting eighth-seeded Olivier Rochus of Belgium 4-6, 6-2, 6-3. The 19-year-old American rallied past Rochus from 3-1 down in the third set to win the final five games.

Sam Querrey lost his first-round match against Russia's Denis Istomin 5-7, 6-3, 7-5. Julien Benneteau of France also defeated American Ryan Sweeting 7-6 (3), 7-6 (5).

With files from The Canadian Press.