INDIAN WELLS, CA, USA -- Former World No.9 Timea Bacsinszky of Switzerland had to draw on all of her experience to get through her opening-round match at Oracle Challenger Series Indian Wells, a WTA 125K Series event, on Monday.

Bacsinszky fought back from 0-4 down in the final set to overcome 14-year-old American wild card Cori Gauff, 6-3, 1-6, 6-4, after two hours and 19 minutes of play, and advance to a second-round match with another former Top 10 player, No. 4 seed Kristina Mladenovic of France.

Gauff is one of the most promising up-and-coming players, becoming the youngest-ever US Open girls' singles finalist in 2017, then winning the girls' singles title at Roland Garros in 2018. But it was Bacsinszky who drew from her up-and-down career to turn the tide of their match and pick off the last six games in a row, holding at love to seal victory.

Bacsinszky got 71 percent of her first serves into play and had a slightly higher winning percentage on first serve than the teenager. The 114th-ranked Swiss, on the comeback trail from hand surgery, thus claims a crucial comeback win as she aims to re-enter the Top 100 with a solid showing this week.

The battle between Bacsinszky and Gauff was just one of the numerous three-set tussles which took place in Monday's opening-round matches at Indian Wells. 18-year-old Olga Danilovic of Serbia, who won her first WTA singles title aged 17 at the Moscow River Cup last year, fought back for a 4-6, 6-3, 6-1 victory over American Caroline Dolehide, overcoming nine double faults.

Kristie Ahn survived a topsy-turvy all-American battle with 2017 French Open girls' singles champion Whitney Osuigwe, 3-6, 7-6 (5), 7-5. Osuigwe served for the match three times in the second set before Ahn won it in a tiebreak. Ahn then clinched the final set 7-5, having led 4-1, to earn a grueling two-hour and 28-minute victory.

Russia's Natalia Vikhlyantseva also needed two hours and 28 minutes before outlasting American Lauren Davis, 5-7, 6-4, 6-4. American wild card Catherine McNally won over Bulgaria's Sesil Karatantcheva by that exact same scoreline, after two hours and 17 minutes of play.

Allie Kiick of the United States eliminated the defending champion, former World No.5 and 2012 French Open finalist Sara Errani of Italy, 6-3, 5-7, 6-2. And former Top 15 player Yanina Wickmayer of Belgium also claimed a three-set win, beating France's Fiona Ferro, 1-6, 6-3, 6-3.

Two Americans had straight-set wins. Sachia Vickery defeated Israel's Julia Glushko, 6-3, 6-2. And Jennifer Brady, back in the Top 100 after a round-of-16 showing in Dubai, ousted 17-year-old compatriot Katie Volynets, 6-3, 6-3.