Andy Roddick shook off some early rust before ensuring experience triumphed over youth at the San Jose Open with a hard fought 6-7 7-6 6-4 victory over 19-year-old American compatriot Denis Kudla on Wednesday.

Kudla, who reached the second round with a win over fellow teen Jack Sock a day earlier, is one of several young players showing off their potential at the event and he nearly scored a huge upset against the 29-year-old three-time champion.

In a matchup of players heavily reliant on their serve, neither man was broken through the first two sets, which were both decided by tight tiebreakers.

Roddick, who blasted 14 aces, fell 2-0 behind in the third set but responded by winning five of the next six games to finally see off the spirited challenge of his youthful opponent.

After receiving a bye in the first round, the second seeded Roddick took to the court for the first time since a hamstring injury forced him to retire from the second round of last month's Australian Open.

Roddick rolled his ankle and needed a lengthy medical timeout late in the second set but showed plenty of determination as he saved 12 of 13 break points during a match that lasted two hours and 42 minutes.

"I stayed out there and did what I could, and I think he let it get away from him a little bit," Roddick told reporters. "Probably the best thing I did was exist out there."

Defending champion Milos Raonic had an easier passage to the quarter-finals, the big-serving Canadian staving off some stubborn late resistance from Tobias Kamke in a 6-2 7-6 victory over the German.

The third seed sent down 18 aces and prevailed 9-7 in a fluctuating second-set tiebreaker that took the contest past midnight.

Earlier, American world number 85 Sam Querrey continued his prolonged slump with a 5-7 6-3 7-5 defeat to Denis Istomin of Uzbekistan.

In other matches, 19-year-old American Ryan Harrison upset Belgian eighth seed Olivier Rochus 4-6 6-2 6-3, Matthew Ebden defeated Dudi Sela 6-7 6-2 7-6 and France's Julien Benneteau edged Ryan Sweeting 7-6 7-6.

World number 13 Gael Monfils was the tournament top seed but the Frenchman withdrew from the event with a knee injury on Wednesday and will also miss next week's tour stop in Memphis.

(Writing by Jahmal Corner in Los Angeles; Editing by John O'Brien; To comment on this story email sportsfeedback@thomsonreuters.com)