Serena Williams of the US serves to Italy's Sara Errani in the women's singles quarterfinal match at the French Open in Paris on Wednesday. Williams won 6-1, 6-3. Photo: IC

Top seed Serena Williams secured her place in the semifinals of the French Open on Wednesday by defeating Italian 17th seed Sara Errani 6-1, 6-3.

Williams, who is looking for her third title at Roland Garros and 20th Grand Slam crown, will meet either 23rd seed Timea Bacsinszky of Switzerland in the last four.

The American had lost the first set in each of her last three matches in Paris but on this occasion she meant business right from the off, breaking immediately to lead 2-0 on the central Court Philippe Chatrier.

The diminutive Errani, who was the runner-up at Roland Garros in 2012 and lost to Williams in the semifinals a year later, broke back straight away but once more she could not hold her own serve and fell 3-1 behind.

Williams then saved another break point against her in the following game with a brilliant cross-court forehand and, with Errani struggling against her ­opponent's power, she broke again ­before serving successfully to take the first set in just 27 minutes.

The second set was tighter, going with serve until Williams broke in the seventh game to lead 4-3, and she then went on to clinch victory on her fourth match point in a marathon ninth game as the match ­concluded in just one hour and five ­minutes.

Williams, who has now won all nine of her meetings with Errani, said, "In the last three matches I lost the first set and today I knew I needed to play very well because she is very good here at Roland Garros so it was very important for me."

Williams is the heavy favorite to win the title, with the other semifinal pairing seventh seed Ana Ivanovic, the Serbian who was the French Open champion in 2008, with Czech 13th seed Lucie ­Safarova.

Bacsinszky toppled little-known Belgian Alison van Uytvanck 6-4, 7-5 in the most unexpected French Open quarterfinal to set up a semifinal showdown with Williams.

Bacsinszky produced a fearless brand of baseline tennis to became the first Swiss woman since Martina Hingis in 2001 to reach the last four at Roland Garros.

World No. 93 Van Uytvanck was ­bidding to become the lowest-ranked woman to reach the semifinals of the clay court major.