The other match, featuring Angelique Kerber and Simona Halep, went to a third after the Romanian had a scrappy start. Halep pointed her right index finger at her temple when she eventually completed a 6-7 (2) 6-3 6-2 comeback to reach the semifinals, too.
"So I give less importance to that". The fact that I could win that long game, I won the next one easily, so it was a little bit of mental part in the last game. Serena Williams is a three-time French Open champion, Jennifer Capriati won in 2001, and the legendary Chris Evert retired with a 94.5% winning record on clay, triumphing seven times at Roland Garros.
Rain has stopped play early on Wednesday.
Halep, who has lost all three of her Grand Slam finals - including the Australian Open, to Caroline Wozniacki, in January - arrived in Paris on a hot streak, reaching at least the quarter-finals in her last nine claycourt tournaments and losing only one set on her way to facing Kerber in Paris.
"I am very pleased to be in another final in Paris", said Muguruza who has yet to drop a set in the tournament and claimed her first win over Sharapova in 4 meetings.
But they hadn't played since 2014, back before Muguruza was as confident and successful as she is these days.
"It's not that important, because it's constantly this thing going on", said Muguruza.
Sharapova certainly didn't do that.
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England begin their campaign against Tunisia before facing World Cup debutants Panama and much-fancied Belgium in Group G. That [opponents winding him up in Russia] is not going to be a problem.
This time, she made no mistake.
It took her 29 minutes just to gain a game, and by then she already trailed 4-0. Muguruza isn't giving he opponent many chances to breathe, and that's the reason for her quick success in these recent matches.
The American pair have contrasting styles, with Stephens' game based on her athleticism and ability to get many balls back, while also turning defence into offence fairly quickly.
"Kind of a weird day", Muguruza said.
On Wednesday, Halep looked anything but the top seed, slipping 4-0 down in the first set before she rallied to defeat Kerber, a two-time major victor who had exited in the first round in Paris in the last two years.
Here's another key category in which Muguruza has the upper hand: 2-0 in major championships.
The victor of Thursday's semi-final will also decide the world number one spot which Muguruza held for four weeks previous year.