Sachia Vickery advanced to the second round of the Guadalajara Open AKRON after Danielle Collins was forced to retire due to a lower back injury.
Ranked No.175, Vickery took her spot in the main draw after Beatriz Haddad Maia withdrew with a hand injury.
"Honestly, I was getting ready to leave tomorrow, I already had my flight," Vickery said. "I was ready to go home. I came this morning and, unfortunately, Bia also hurt herself, and I wish her a speedy recovery. Sometimes that happens, some weeks on the tour."
Vickery trailed 5-2 in the first set before mounting a comeback to force a tiebreak. There, Vickery saved two set points before taking it 7-6(7).
After already calling a medical timeout and receiving treatment earlier in the set, Çollins could not continue.
In as a lucky loser, the 28-year-old American will face her compatriot, Caroline Dolehide next. Dolehide won her opener over No.43 Peyton Stearns, winning 6-7(1), 7-6(5), 7-6(2).
No.5 seed Belinda Bencic withdrew ahead of her opening match against Taylor Townsend, citing gastrointestinal illness. She was replaced in the draw by lucky loser Elvina Kalieva. Townsend and Kalieva's second-round match was suspended for rain with the American leading 6-1, 5-5.
More notable results from Day 2
Sofia Kenin rebounded from her quick turnaround after making the San Diego final on Saturday to earn a win in Guadalajara on Monday. Kenin advanced with a 6-4, 6-3 win over Canada's Carol Zhao in the first round. She will next face No.12 seed Anhelina Kalinina.
No.7 seed Veronika Kudermetova held off Eugenie Bouchard in 2 hours and 49 minutes, winning 6-2, 6-7(4), 6-4 in the second round.
Colombia's Emiliana Arango earned her third tour-level main-draw win of the season by defeating No.11 seed Anastasia Potapova 6-4, 6-3 in the first round. Ranked No.180, the 22-year-old will next face Sloane Stephens.