Defending champion Serena Williams showed no mercy to Austria's Barbara Schett, crushing the Austrian 6-0, 6-0 to power into the last 16 of the French Open women's singles.

Serena, who has won the last four Grand Slams in a row and who had dropped only eight games in her opening two rounds, was even more dominant against 57th-ranked Schett, blasting her off the Philippe Chatrier centre court in just 40 min.

Even without playing anywhere near her best Serena was far too good for a hopelessly outwitted Schett, who said she felt as if she was playing a man.

"She hits her shots harder than any of the other girls - yes, you really could say it's almost like playing a man," said the 27-year-old from Innsbruck after failing to make it into the fourth round for the third time.

"Whether you lose 6-0, 6-0 or 6-2, 6-2 it doesn't make much difference.

"From the first point to the last she put me under so much pressure, she moved well and I couldn't finish my points. I had no rhythm at all - but I have huge respect for her," Schett readily conceded.

The 21-year-old Serena next meets 16th seed Ai Sugiyama of Japan, who swept past US 18th seed Meghann Shaughnessy 6-1, 6-4.

Serena won the opening set in just 21min, producing nine outright winners to just one for Schett, and the pattern continued in the second as she tore through against the former world number seven, smacking down three aces in the process to offset two double faults.

"I just played really good today. Barbara and I normally have a tough match," grinned a bright orange-clad Serena, who ecstatically blew kisses to the crowd before heading off to sign autographs courtside.

"Today was just my day. Hopefully, I can keep it up."