TORONTO, Canada - In the best win of her comeback so far, American Sloane Stephens survived a tense battle against No.14 seed Petra Kvitova in the second round of the Rogers Cup, 7-6(4), 3-6, 6-2.

The former World No.11, who missed nearly a year of action due to a foot injury before returning at Wimbledon, hadn't won a match coming into her third tournament of the season this week, but ousted Yulia Putintseva in her opener before scoring the upset over the 2012 champion to close out play on Grandstand.

"Obviously, I haven't played this much tennis in a long time, so it's tough, but I feel good, my body feels good," Stephens told WTA Insider after the match. "I'm just excited to be in the third round of a tournament, improving from my 900 ranking, going up, so I'm pleased with that and can't ask for much more.

"Just focusing on my game and being aggressive, focusing on myself is the most important thing."

Though Stephens broke the Kvitova serve in the first game of the match, the Czech got back on serve in the sixth game, and forced the American to serve to stay in the set twice in the later stages.

Neither player was able to generate a break point over the last six games of the opener, but it was Stephens who twice led by a minibreak in the tiebreak, as some untimely unforced errors came off the Kvitova racquet.

The Czech forced Stephens to serve out the tiebreak, which the American did with aplomb, as she held the final two points of the tiebreak to take a one-set lead in their first WTA meeting.

Kvitova pounced on early momentum to begin the second set, as she won three of the first four games and looked to force a decider.

Though Stephens quickly pulled even in the second set by claiming the next two games, the two-time Wimbledon champion showed her mettle to force a final set, as she pocketed the final three games in decisive fashion.

Kvitova largely turned the match around in the middle stages on serve, as she raised her first serve percentage from 43% in the opener to 71% in the middle set.

She also proved more effective in returning the Stephens serve in the second set, as she won more than half the points on return in set two, up from 33% in the opener.

However, Kvitova's momentum stalled to begin the decider, as Stephens' increased consistency and attacking tennis from the baseline began to win out in several lengthy rallies. 

The American scored the first break in the third game of the decider, and after a big serve saved break point in the next game, she added an insurance break in the seventh game with the point of the match to score the upset victory in two hours, 20 minutes.