Serena Williams reached the third round of the Rome Open after being pushed to dig deep to beat one of her toughest rivals Nadia Petrova on Wednesday.

The 9th-seeded Williams had lost her last two meetings with Petrova, as well as two of their three previous clay court meetings, and an upset loomed as the big-serving Russian won the first set, 6-4, and held triple break point at 1-all in the second set; but Williams came back swinging, saving five break points in that game and never looking in danger again, eventually winning 4-6, 6-2, 6-3.

"When I lost the first set, I just thought, 'Stay in there and just don't give up, you'll have a chance,'" Williams said afterwards. "I just didn't want to give up. I never do want to give up, nor have I ever wanted to give up. I wanted it today."

Williams is now 15-0 on clay this season Oakley Eyepatch 2 Sunglasses, going 5-0 to win Charleston, 2-0 in Fed Cup play, 6-0 to win Madrid and 2-0 so far here. The last time anyone pulled off a perfect clay court season was Justine Henin's 24-0 run in 2005.

"I love Europe and to be able to play the whole swing here is really cool," Williams said. "I've definitely developed a lot of confidence on clay. I like it a lot. Well, I've always liked it. It's just that I haven't won a lot of tournaments on it, but now I'm getting more wins and hope to change that going forward."

The 13-time Grand Slam champion continued to describe her passion for the sport. "I am so inspired to be out there," she said. "The only incentive I have is that I love tennis and I love playing. There are a lot of times in life you don't get the chance to do what you do best, but this is definitely where I belong."

Next up for Williams is Anabel Medina Garrigues. Curiously, the two veterans - Williams is 30, Medina Garrigues 29 - will be playing for the first time.

Venus Williams also moved through to the third round, battling back from 5-3 down and needing six set points to close out the first set but then rolling past Ekaterina Makarova for a 7-6(7) 6-1 victory.

"I really had to buckle down and stop making so many mistakes in the first set. Once I did that, it was good," Williams said after the match. "Rome is my favorite city in the world - but as much as I would love to be exploring it, it's definitely better to be playing in Rome. So I am very happy to be here."

Since losing to Monica Seles in the quarterfinals of the 2002 Australian Open, Williams has gone 36-2 against left-handers, her only losses coming to Petra Kvitova at Memphis in 2008 and to Angelique Kerber at Madrid last week.

Next up for Williams is No.5 seed Samantha Stosur. Williams leads the overall head-to-head, 4-1, but Stosur won their only 2012 meeting.

Other winners on Day 3 were No.13 seed Ana Ivanovic, Chanelle Scheepers and Sorana Cirstea. Ivanovic cruised past Spanish qualifier Silvia Soler-Espinosa 6-2, 6-1, and next has No. 2 seed Maria Sharapova. Sharapova leads the head-to-head, 4-2, but Ivanovic won their only clay court meeting.

"It's nice to get back-to-back wins here, especially after a tough first round against Svetlana," Ivanovic said. "The next one will be even tougher. Maria and I had a great first set in Indian Wells before I had to retire, and she has been playing better and better on clay. But I'm playing well right now too.

"I hope we can take the level up."

At night No.1 seed Victoria Azarenka beat Shahar Peer 6-1 Oakley Jupiter Squared black Sunglasses, 6-2, never facing a break point and winning nearly twice as many points in the match (57 to 29).

Azarenka withdrew from the tournament afterwards with a shoulder injury.