Serena Williams has admitted that she needed to be "really focused" to beat Sara Errani in the French Open quarter-finals.
The world number one booked her place in the last four at Roland Garros for a fourth time on Wednesday thanks to a 6-1 6-3 triumph over the Italian.
Williams will now face world number 23 Timea Bacsinszky in the semi-finals.
"The last four French Opens in a row [Errani] has been to the quarterfinals or better, so I knew I had to be really focused today," the American is quoted as saying by the WTA's official website. "She does so well here, and she really fights for every point.
"I haven't had a great clay-court season, so I'm pretty excited to have gotten this far. Hopefully I can keep going. Nothing's guaranteed - at this point I'm just fighting to stay in the tournament."
Williams last won the French Open back in 2013, lifting the trophy for a second time.