Peyton Stearns shouts out college tennis as perfect prep for Roland Garros upset

WATCH: Peyton Stearns speaks on her second-round upset of Jelena Ostapenko at Roland Garros.

What prepared Peyton Stearns to upset former Roland Garros champion Jelena Ostapenko in Paris on Wednesday to reach the third round at a Grand Slam for the first time? College tennis.

The former University of Texas star credited her two years in Austin, where she led the Longhorns to two NCAA team titles and won the 2022 NCAA individual crown, with giving her the extra push needed to finish off a 6-3, 1-6, 6-2 upset of the No. 17 seed in front of a raucous crowd on Court 14.

The 21-year-old American hit more winners than Ostapenko (30 to 29), less unforced errors (21 to 28), and stayed laser-focused in the face of both her increasingly-irritated opponent, and a passionate crowd of French fans trying to urge her to victory (who, at one stage, did the wave).

"You see that a lot, people screaming at you, saying things," Stearns told Tennis Channel's Jon Wertheim afterwards. "I thrive off that energy, and I love it out here."

At the start of the season, Stearns was ranked outside the Top 200 in the WTA rankings, but she entered Paris ranked No. 69 on the back of results including two ITF circuit titles; two other finals, including a runner-up finish to fellow former collegian Emma Navarro in April at a $100,000 event in Charleston; and a runner-up finish to Tatjana Maria in Bogota.

Now, she's making further waves in Paris: The win over Ostapenko was Stearns' first-ever Top 20 victory, and her second against a Top 50 player in as many matches so far at Roland Garros after she also beat Katerina Siniakova in the first round.

"I really couldn't think about who I was playing, where I was playing," Stearns said. "The nerves crept in in the second set; I was able to rebound, luckily, for the third. I got my mind right, and I'm super happy with myself and my team right now."

While Stearns' credited her Longhorns career for helping her in the moment on Wednesday, she also shouted out the road to get to this point, and work she's put in to get to this point in the last 12 months since turning professional.

"I think developing a solid team around me that I trust—they want me to do the best—putting in the work, coming out on court every day and trying my best even if it doesn't look pretty, and that's that," she said.