Serbian top seed Ana Ivanovic crashed out of the Italian Open in her first game, losing 6-4 5-7 6-2 to Bulgarian qualifier Tsvetana Pironkova.

Russian world number two Maria Sharapova survived a scare to beat unseeded Slovak Dominika Cibulkova 6-2 3-6 6-4 in her second round match but the other top seeds had less trouble.

Former world number one Venus Williams beat Australian Samantha Stosur 6-4 6-1 while her fifth-seeded sister Serena also joined Sharapova and Pironkova in the third round with a resounding 6-2 6-0 win over Ukrainian Alona Bondarenko.

Serbian title holder Jelena Jankovic, the fourth seed, progressed in straight sets too with a 6-1 6-4 victory over Italy's Flavia Pennetta.

Russian third seed Svetlana Kuznetsova, who lost to Jankovic in last year's final, had an easy 6-2 6-0 win over Belarusian Olga Govortsova.

Ivanovic made an untidy start with too many groundstrokes finding the net or going long and she soon went down a break, but she broke back in the ninth game only to fail to hold immediately after and concede the set.

The world number three twice surrendered a break advantage in the second set and let a string of chances to take the Bulgarian's serve again go begging before she finally managed to level things up.

But the unforced errors kept flowing and she was broken three times on the way to losing the decider.

"I felt quite flat out there and I found it a struggle to find my rhythm and find something inside to fight," Ivanovic said.

"I really struggled with my intensity today and obviously that caused a lot of errors. It's something I have to work on. Now I have 10 days to prepare for the French Open."

After an early trade of breaks, Sharapova took the upper hand against Cibulkova with some big hitting, although she needed seven set points on her serve to wrap the set up.

But the Slovakian was not deterred and, after another exchange of breaks in the middle of the second set, she took Sharapova's serve with a drop shot before serving out to level the match.

The Russian then edged a topsy-turvy final set of seven breaks to creep home.

"It isn't easy to hold serve against someone who hits back so well," Sharapova said. "She definitely [outplayed] me a few times today. But I know where I went wrong."

Seventh seed Venus, returning from over a month on the sidelines with an unspecified medical problem, was put to the test immediately by Stosur, dropping serve in the opening game.

She broke back in the eighth game and cruised to victory after that, breaking Stosur again to take the first set before dominating the second.

Reuters