Serena Williams faces Garbine Muguruza in Saturday's French Open final

Serena Williams can make tennis history in Paris on Saturday when a win over Garbine Muguruza in the French Open final would help her finally to equal Steffi Graf's Open era record of 22 titles.

The world No 1 reached yet another slam final with a 7-6 (9-7) 6-4 victory over Kiki Bertens while Muguruza overcame 2010 finalist Sam Stosur 6-2 6-4 to set up a repeat of the Wimbledon final.

Williams won her 21st slam singles title at the All England Club last year but since then has lost to Roberta Vinci in the semi-finals at the US Open and Angelique Kerber in the final of the Australian Open.

Her opponent Muguruza handed Williams her heaviest ever loss at a slam at Roland Garros two years ago, beating the great American 6-2 6-2 in the second round.

That loss was, and remains to this day, the most lopsided defeat of Williams' 338-match Grand Slam career.

"I learned so much from that match," said Williams. "I hate to lose, but when I do, I hope it was worth it.

"That match was definitely one of those that was kind of needed and worth it."

Since that setback, Williams has won 47 of 50 matches at majors, collecting four trophies along the way to boost her total to 21. Only Graf and Margaret Court, with 24, own more.

After dicing with elimination in her quarter-final against world No 60 Yulia Putintseva, Williams again was below her best against No 58 Bertens in the semi-finals on Friday.

"You know, if I get there it will be great. I guess you can say it took me a while to get to 18, considering, you know, I'm the only one on tour that had 18," she said.

"I guess it's how you look at it. The same with 21 and trying to get to another one. Nothing I can do about it. The only thing can I do is just play to win the tournament and that's it."

Neither woman moved well and Williams confirmed after the match that she has been hampered by a thigh problem.

Both women were playing their third match in as many days while Muguruza, in the bottom half, has been less affected by the weather and had a day off on Thursday.

The highest-seeded player Williams has faced so far was 18th seed Elina Svitolina, so world No 4 Muguruza represents a significant step up.

The 22-year-old is a power player like Williams and has been hugely impressive in her run to Saturday's final.

Williams' coach Patrick Mouratoglou said: "She's a great player but, as always, I want to think that the keys of the final are in Serena's hands. In positive or in negative, throughout her career it was always up to her."

Muguruza gave a fighting response, saying: "I think that she and I are players who like dictating the game. If the coach says that the victory is in the hands of Serena, okay, he's allowed to say that.

"But I think I'm going to fight for each point. There will be moments when she'll be dominating, and maybe at times I will be dominating. I think I can be a tough opponent, too."

Muguruza, the first Spanish women to reach the singles final here since Conchita Martinez finished runner-up to Mary Pierce in 2000 and she will aim to become the first Spanish winner of a Grand Slam title since Arantxa Sanchez-Vicario in Paris in 1998.

And Muguruza is confident she will handle the occasion better than she did at Wimbledon. "It was a first final," she said. "The opponent was tough to beat. I was tense. It was difficult for me to manage stress.

"I have learned a lot how to control my emotions inside the court and outside the court. It's true that Garbine has changed. Garbine has changed quickly. And that's fantastic for me."

Follow our live blog of the women's final between world No 1 Serena Williams and Spain's Garbine Muguruza this Saturday from midday on skysports.com/tennis, our app for mobile devices and iPad and our Twitter account @skysportstennis.