Stanford grad Nicole Gibbs was down 4-1 in the third set after Claire Liu recovered from a love-40 deficit.
She eventually got back into the first-round match at the Bank of the West Classic on Monday and rallied for a 4-6, 6-2, 7-6 (5) victory over Liu.
Gibbs, ranked No. 128, was coming off a victory at an ITF tournament in Baton Rouge.
"My body was not holding up to the surface changes so after clay I wanted to get a good jump on hardcourt," Gibbs said of playing in Louisiana. "It paid off. I played so many three-set matches in the heat and I got the feeling that my legs got through that, it gave me so much confidence, even down 2-5."
Liu, currently the No. 1 high school prospect in the nation, was coming off the junior championship at Wimbledon.
"She's an amazing player," Liu said of Gibbs. "I had my chances. She played fearless and played well in big points."
Gibbs will play the winner of Tuesday's match between CoCo Vandeweghe and Ajla Tomljanovic in the second round.
Maria Sharapova, continuing her comeback from a 18-month suspension, took care of American Jennifer Brady, 6-1, 4-6, 6-0, and will meet Ukraine's Lesia Tsurenko on Wednesday afternoon.
"Being away from the game so much my focus is solely on the tournament I am in," Sharapova said. "It's just as big playing here. I have a history with the tournament, with the people and with the fans."
After serving her suspension, Sharapova played in three tournaments and suffered a tear in her muscle in the third one, taking her away from the game for another two months.
This is her return to the court from the injury.
"I felt like I was just getting back into it and it was a good feeling getting into that routine," Sharapova said. "The last eight weeks has been frustrating but I kept doing the work."
The night session drew 2,187 fans, the second-largest Monday night crowd in the tournament and the most since 2009, when Sharapova was also the Monday night draw.
"I feel at home here," she said. "When you see a large crowd on a Monday night it is special. It's an opportunity I have and I'm thankful for it."
Atherton resident CiCi Bellis, seeded eighth in the tournament, highlights Tuesday night action. The 44th-ranked teenager meets France's Alize Cornet, ranked 45th, at 7 p.m.
Bellis, ousted in the first round of Wimbledon by former world No. 1 Victoria Azarenka, reached the semifinals on grass in Mallorca, where she beat No. 26 Carla Suarez Navarro in the first round.
A victory over then-No. 18 Kiki Bertens of Netherlands highlighted Bellis' appearance at the French Open, where she reached the third round.
Bellis and Cornet, who has five career WTA singles titles, will be meeting for the first time. Cornet has not won a tournament since January of 2016.
Cornet has been knocked out in the first round of her past three tournaments but did reach the Round of 16 at the French Open. She played at Stanford for the first time last year.
Stanford grad Carol Zhao and Cardinal sophomore Melissa Lord are playing together in doubles and meet Russia's Anastasia Pavlyuchenkova and Ukraine's Olga Savchuk at 11:30 a.m. on court 6.
Kristie Ahn, another former Stanford star, makes her first appearance at the Bank of the West on Tuesday. She'll play qualifier Veronica Cepede Royg of Paraguay on the stadium court at approximately 3:30 p.m.
"The band is back together this week," Gibbs said of the Stanford reunion. "I didn't want my stay to end in the first round. I want to stay here as long as possible."
Gibbs and Ahn will also be playing doubles this week.
"She's had a fantastic year, doing a lot of winning," Gibbs said of Ahn. "It's exciting to see her determination and hard work. She deserves this more than anybody. I'm her No. 1 fan."
In other first-round matches, American Kayla Day defeated Japan's Misaki Doi, 6-4, 6-2; Ukraine's Lesia Tsurenko downed Spain's Lara Arruabarrena, 6-3, 6-3; Croatia's Ana Konjuh won when New Zealand's Marina Erakovic retired one game into the second set; and Russia's Natalia Viklyantseva topped American Danielle Lao, 6-4, 6-3.
In doubles play, Ukraine's Lyudmyla and Nadiia Kichenok beat Gabriela Dabrowski (Canada) and Yifan Xu (China), 6-4, 6-4; and the American duo Abigail Spears and CoCo Vandeweghe bested Eva Hrdinova (Czech Republic) and Asia Mohammad (USA), 6-3, 6-0.