dsabedra@mercurynews.com

STANFORD -- It was all going fairly routinely for Agnieszka Radwanska in the first set of her first match at the Bank of the West Classic on Wednesday night.

But victory turned out to be anything but routine for the tournament's top seed.

After winning five of the match's first six games, Radwanska had to dig deep to beat veteran Francesca Schiavone 6-4, 6-3.

"The first match on the hard courts is always tricky," Radwanska told the fans at Stanford's Taube Family Tennis Stadium after improving to 4-4 against her Italian opponent.

Schiavone seemed all but done, at least in the opening set, as Radwanska cruised to a huge lead. But with a chance to serve out the set at 5-1, the Polish star ranked fourth in the world watched Schiavone mount a serious comeback that had fans applauding her grit.

Schiavone, 33, hit a forehand winner while charging toward the net and then unleashed a shot on the line for a break of her own.

Suddenly, the match got interesting as Schiavone dazzled with an array of unreturnable lobs.

"Of course, I should have finished that set much earlier, but I didn't," said Radwanska, who was playing for the first time since losing to Sabine Lisicki in the semifinals at Wimbledon three weeks ago.

Schiavone, ranked 59th, broke serve again to cut the deficit to 5-4 but double faulted to hand the set to Radwanska.

That continued a stretch in which neither player held serve for six consecutive games. The streak ended when Radwanska needed two deuce points to hold for a 3-2 second-set lead.

"Serve was not the key to this match at all," said Radwanska, who will play Varvara Lepchenko in the quarterfinals.

Earlier Wednesday, qualifier CoCo Vandeweghe, who made a surprise run to the Bank of the West final last year, was ousted by fifth-seeded Sorana Cirstea 6-3, 6-3. Cirstea took charge early, winning the first three games, and withstood every comeback attempt.

"She's a very good player and is not easy to play because she serves very big and she has a big game," Cirstea said.

Lepchenko, seeded sixth, struggled to close out her match against Tamira Paszek but held on for a 6-4, 6-4 victory.

"I don't know what it is about me these couple of days," said Lepchenko, who also wasn't satisfied with her opening-round win over Michelle Larcher De Brito a day earlier. "Hopefully it will change."

After building a commanding 5-2 lead in the second set, Lepchenko lost two games in a row before ending the match.

"I was thinking to myself, 'I don't really want to lose this set, so I don't have to play three sets,'" Lepchenko said. "I'll have to change my set of mind for the next match."

Lepchenko, 27, has overcome bigger challenges in her life. Born in Tashkent, Uzbekistan, she and her father left their homeland in 2001 to seek political asylum in the United States. She became a U.S. citizen nearly two years ago.

"I'm going to have to play better to make it here," she said.