Williams clocked 206 kmh (128mph) during her second round 6-1, 7-6 (10/8) win over compatriot Ashley Harkleroad on Court Suzanne Lenglen.

"I loved it," said Williams whose record coincided with her allowing Harkleroad back into the match from 2-5 down, and holding match points, to having to fend off four set points when she should have safely back in the locker room.

"That's where I lost my focus a little bit because I saw the 206. I was so excited. When I was younger I was always trying to serve harder and harder.

"Now that I'm not trying to serve hard, it comes hard. It was unexpected," added Williams who registered the new mark in the fifth game of the second set when she was leading 4-1.

Williams set the old mark of 204kmh (127mph) in 1998 in a quarter-final win against Mary Pierce in Zurich which was broken by Dutch veteran Brenda Schultz-McCarthy who hit a serve of 209kmh (130mph) in Cincinnati last July.

However, that came in the qualifying competition.

Williams, the 26th seed, next faces either Serbian fourth seed Jelena Jankovic or Colombia's Catalina Castano for a place in the last 16.