Serena Williams unphased by arduous French Open schedule

The world number one was unable to take to the court on Monday or Tuesday because of rain and must now potentially play four matches in four days.

Williams said: "When we play regular tournaments you play four, five matches in a row. I t's something you just get used to. It's totally fine I think for me and for everyone."

If they are all as straightforward as her 6-1 6-1 victory over Elina Svitolina in the fourth round, then it certainly will not be any problem at all.

Williams needed just 62 minutes to see off the Ukrainian, who is coached on a part-time basis by a former French Open nemesis of Williams, Justine Henin.

But Svitolina did not possess the same finesse as Henin and could find no answer to the sheer power of her opponent.

The forecast indicates there could be more disruption from the weather over the next two or three days, and Williams said she would draw the line at playing two matches in one day.

"I have done that once before, actually," she said. "Charleston I think I played like the 1pm and the 7pm match. It was crazy.

"No, I don't think they would do that, though, here. This is a grand slam, and I think we would have to find a different solution."

Williams next meets Kazakhstan's Yulia Putintseva, who upset 12th seed Carla Suarez Navarro 7-5 7-5.

Putintseva is one of four unseeded players through to the quarter-finals along with Shelby Rogers, Tsvetana Pironkova and Kiki Bertens.

Williams has substantially more match wins in slams than all the other seven quarter-finalists put together and is a very strong favourite to win the tournament and equal Steffi Graf's tally of 22 titles - a record which has been just out of her grasp for the best part of a year since her last grand slam title at Wimbledon.

Putintseva took on the American in Indian Wells this year and forced a tie-break in the opening set before being overwhelmed in the second.

The 21-year-old said: "Of course she's the best player. She's a legend. I'm just going to go there and show my game, show my best, and we'll see what's going to happen. I have nothing to lose obviously against her."

Williams has yet to drop a set on clay this season, but a woman in almost as good form is Bertens, who added 15th seed Madison Keys to her list of scalps.

Bertens won the title in Nuremberg the week before Roland Garros as a qualifier and has won 11 straight singles matches and 18 including doubles.

Both Simona Halep and Eugenie Bouchard followed up winning the title in Nuremberg with long runs in Paris in the last couple of years, and Dutchwoman Bertens said with a smile: "Maybe there is something in the food there. I have no idea.

"I felt good there that week. I'm coming here with a lot of confidence. I'm still playing here. It's just amazing for me."

Bertens next meets eighth seed Timea Bacsinszky, who defeated Venus Williams 6-2 6-4 to deny the veteran American a first quarter-final appearance at Roland Garros in 10 years.

Bacsinszky's run to the semi-finals 12 months ago was a big surprise but that is not the case this year.

Venus, meanwhile, had sympathy for Halep and Agnieszka Radwanska, who both suffered upsets on Tuesday and were furious at having been made to play in the rain.

"I think the conditions were not playable yesterday," said Venus.

"It was really bad. It's hard to see. The balls are wet, the courts are wet. I wasn't out there the whole time that some of the matches were on, but it just seemed terrible.

"It should be fair. Some players shouldn't have to play in that weather and others not."