Men's top seed Roger Federer meanwhile had another stroll in the park as he outclassed Italian Potito Starace 6-2, 6-3, 6-0 to set up a last 16 clash with Russia's Mikhail Youzhny.

The 22-year Belgrade-born Jankovic has been in impressive form this year winning three titles in Auckland, Charleston and most recently in Rome and she had beaten Williams on the last two occasions they had met.

First upon the centre-court and with the sun shining for once, Jankovic won the toss, chose to receive and the tactic paid off as the 25-year-old Williams served up a dreadful game.

That service break was all she needed to lift the first set, but it was Williams, a five-times Grand Slam champion who has never been fully at ease on clay who struck first in the second.

Both players struggled to hold on to their serves, and it was the American who had the last word with a third service break in four games to level the scores.

But it was the Serb who proved the stronger in an impressive final set breaking the Williams serve in the third and fifth games to move 4-1 up.

That broke Williams's resistance and two games later it was all over.

"I stayed mentally very strong in third set and I really went for my shots," Jankovic said.

"I was a little bit tired in the second set, but I just went for it in the third and it paid off.

"It was an amazing third round match and it was a shame that Venus had to go out so early. It's always good to beat one of the Williams sister.

"I got a little bit tired in the end. It's tough on clay," Williams said, adding that she would not play another tournament before Wimbledon. Also into the last 16 was 29-year-old Tathiana Garbin of Italy who reached the fourth round of a Grand Slam event for the first time at her 28th attempt with a 6-3, 6-0 win over France's Stephanie Cohen-Aloro.

Nicole Vaidisova, the sixth seed, defeated Australia's Samantha Stosur in straight sets to reach the last 16 for the second year in a row.

Li Na was the last Chinese player to fall in Paris going down tamely 6-4, 6-3 to Austrian 20th seed Sybille Bammer.

Youzhny made it through to face Federer by outlasting 2003 champion Juan Carlos Ferrero of Spain 6-7 (3/7), 7-6 (7/3), 6-2, 6-2.

Federer has won all nine matches he has played against Youzhny, but he insisted he would not make the mistake of underestimating his opponent.

"Although I have never lost to him, I have a lot of respect for his game. I like the way he plays, so I will have to be careful," he said.

"He had a strong indoors season, won the title in Rotterdam. Last year he made the US Open semi-finals. He's a fantastic player."

Others into the fourth round were rising Argentine claycourter Juan Monaco and Paul-Henri Mathieu who won an all-French clash against Gilles Simon.

Women's top seed and defending champion Justine Henin of Belgium was scheduled later in the day to take on tall Italian Mara Santangelo, a player she has beaten four times out of four.

Also on the agenda were Serena Williams against Michaella Krajicek of the Netherlands and men's fourth seed Nikolay Davydenko of Russia facing the challenge of French hope Michael Llodra.