Three months ago, Peyton Stearns was a 21-year-old wild card playing in her second WTA Tour 100 event, Indian Wells, back in March. She met Bianca Andreescu, a Grand Slam champion, and lost a trying second-round match in three sets.

On Wednesday, playing in her second Grand Slam singles main draw, Stearns ran into another major champion, Jelena Ostapenko. This second-round match went a little differently, as Stearns took out the 2017 Roland Garros winner 6-3, 1-6, 6-2. It underlined how remarkably far and fast Stearns has assimilated and adjusted to life on the Hologic WTA Tour.

“It was definitely crazy, nerve-wracking, overwhelming -- all of the emotions into one,” Stearns told a handful of reporters afterward. “But I think at the end I settled down and was really able to come to peace with myself and play my tennis instead of who I was playing, where I was playing and whatnot.

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“It’s not super surprising to me. If I go out there and play my game then the best can come. Trying to play not to lose but to win is a big thing. And that’s what happened today.”

That matter-of-fact confidence has landed the outgoing American in the third round at Roland Garros, where she’ll play No.9 seed Daria Kasatkina, a 6-3, 6-4 winner over Marketa Vondrousova, on Friday.

“I think I expected this out of myself, maybe not this early in my career,” Stearns said. “I just left school a year ago. I thought leaving school maybe I’d be in the qualifying for this event with my ranking. So I think I’m ahead of what I projected myself doing.”

Last spring, Stearns became the first University of Texas woman to win the NCAA Division 1 singles national championship. Stearns left the school after completing her sophomore year and, ranked No.209, began the season playing ITF events. By the time she reached Indian Wells, after a quarterfinal appearance the week before in the Austin WTA 250, she was up to No.126 in the world and talked about the expectations she placed on herself.

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“I have a lot,” she said in an interview with wtatennis.com. “The best way I can put my mind at ease is to not have them.

“In Austin last week, I was putting too much pressure on myself, thinking that I can go far, do well. The nerves and the tightness showed up and I wasn’t swinging freely. This week, going into this tournament the only way I’m going to succeed is if I do the right things.”

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It’s a mantra that has carried her to the No.69 ranking. Her record for the year -- the bulk of them ITF matches -- is a gaudy 32-8. If she wins her second-round match, No.2-ranked Aryna Sabalenka will have won 31 matches this season.

Highlights from the past two months include advancing to the final of the Bogota, Colombia WTA 250 (losing to Tatjana Maria), the final of the $100,000 ITF event in Charleston (Emma Navarro) and most recently the quarterfinals in Rabat Morocco WTA 250, where she fell to Sloane Stephens. Stearns’ increasingly lofty ranking may well leave those ITF events in the rearview mirror.

Everyone at the WTA level has talent and the ability to execute game plans, but Strearns has quickly grasped that mentality is what separates the great players from the merely good.

“At least for me, it’s staying in it longer, if that makes any sense,” Stearns said in Indian Wells. “I feel like in college and on the ITF circuit you can get away with certain aspects, but at this level, you’re competing with the best of the best so you can’t take a shortcut in any direction.

“The best way I’ve found to play through it is to trust my game and take each point on its own, even if the last point didn’t go well.”

On Wednesday, Stearns struck 30 winners, one more than Ostapenko. Stearns committed only 21 unforced errors in the match. 

That her greatest success has come on the European clay is something of a surprise. Stearns said she’s played fewer than eight tournaments on red clay over her career, including juniors, and was never comfortable on the green clay found in North America. The ball moves through the court a little faster on red clay and bounces higher. When it’s warm, as it has been in Paris, her big game gets even bigger.

“I think sometimes I surprise myself with how lethal my ball comes off [the racquet],” Stearns said. “And how it really puts them in trouble. Maybe I didn’t realize that earlier on. But playing against top players, it’s true.  It comes off pretty heavy and big … and that’s how I play and definitely helps my confidence.”

When she started out, one thing that drew Stearns to tennis was that, quite naturally, she could hit “the living daylights out of the ball.” Controlling it was another thing.

“It was hard to harness,” Stearns said. “Through my career, playing local tournaments, national, international, I never did amazing. I had a lot of unforced errors. It depended on the day.

“Especially the last year, it’s night and day when I can harness what I have.”