After sitting out almost a year because of an injured right foot that needed surgery in January 2017, she has soared up the rankings and now made it to her second major final in the past ninth months.
"I think the book was 100 percent hearsay, at least all the stuff I read and the quotes that I read, which was a little bit disappointing", said Williams, who played in her first Grand Slam since giving birth past year.
Half an hour later 1-0 had become 6-1 and the challenge of Muguruza, who would have taken over at the top of the rankings with victory, appeared to be fading fast.
She improved in the second set, breaking early on only to be pegged back at 4-4 before Halep held a marathon ninth game and broke for a 6-1 6-4 win. Stephens is second only to Halep in break points converted with 27.
Muguruza is 3-0 in career grand slam semifinal matches. I'm happy to play the final again at my favourite grand slam.More news: Garbine Muguruza beats Maria Sharapova to reach the French Open semis
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No. 28 Maria Sharapova had a good run at this year's French Open, but she fell short in her first quarterfinal match since the 2016 Australian Open after running into defending Wimbledon champion Garbine Muguruza. Sharapova insisted that the book contains no inaccuracies and defended her many references to Williams who has not lost to the Russian since 2004.
"I will try my best", Halep told the crowd at Court Phillipe Chatrier, "and hopefully I will be better than previous year". "Well, she's number one", she said.
Stephens can join Serena Williams and Jennifer Capriati as the only American women to win a French Open title since 1987. So like I said, making the quarter-finals here was a big deal for me. Muguruza has yet to drop a set this tournament and is forcing many unforced errors from her opponent due to being aggressive and hitting the ball deep. She knows she needs to win one of these Slams, and she's confronted this missing element head-on.
"I think it would be unusual for me not to include someone that I have competed against for so many years", said the 31-year-old. Halep then seized her chance, moving 0-40 ahead and then raising her arms in triumph as Muguruza blazed a backhand long. "And obviously making the semis and finals, there is not much more you can ask for in a player".
"I think she's right now probably the best player". I think that's a load of crap, but, you know, it's just me (smiling).
Despite not playing her best tennis, Halep was able to get past Muguruza in straight sets.
Stephens put a higher percentage of first serves into play (76.2 percent) than anyone in the draw other than her first-round victim, Arantxa Rus.