PARIS (AP) - In stark contrast to her previous three matches, top-ranked Serena Williams overpowered Sara Errani on Wednesday to reach the French Open semifinals with a 6-1, 6-3 win.
A two-time champion in Paris, Williams extended her unbeaten record against the 2012 French Open runner-up to nine matches.
The 19-time Grand Slam champion got off to sluggish starts and lost the opening set in her last three matches. She didn't have that problem today.
''It was very important for me to take a very good start,'' said Williams, speaking in French during her on-court interview. ''The last four French Opens in a row she's been to the quarterfinals or better, so I knew I had to play very well today.''
Williams broke for a 2-0 lead but dropped her serve in the next game. She saved a break point in the fifth game with a crosscourt backhand punctuated with a big ''Come On!'' and held after hitting a 121 mph (195 kph) ace.
Errani played deeper in the second set but was broken two more times.
Williams, who will play in her fourth Roland Garros semifinal match against Timea Bacsinszky, finished with 39 winners to Errani's nine.
''The power is of course a big thing,'' Errani said. ''She has a lot of power in the serve. She's serving so strong. And then from the baseline she is hitting so strong, so it's difficult to play.''
In her nine matches with Williams, the 17th-seeded Italian has won only two sets but she was confident she could do better this time after leading by a set and a break the last time they met in April in the Fed Cup.
''I tried to do the same, but of course the conditions were different,'' Errani said. ''Today Serena, with these conditions, played much better, much stronger. So it was difficult for me to make the things that I normally want to do.''
Williams, who claimed her titles in Paris in 2002 and 2013, has won 19 straight Grand Slam matches and is two away from a third consecutive major title.
Bacsinszky, the first Swiss female player to reach a Grand Slam semifinal since Patty Schnyder at the 2004 Australian Open, defeated Alison Van Uytvanck of Belgium 6-4, 7-5. The other women's semifinal will pit seventh-seeded Ana Ivanovic against No. 13 Lucie Safarova.