The Spaniard was ousted in the very first round of the Ostrava Open after a 7-6 (7-4), 6-4 defeat to Petra Kvitova.
Maria Sakkari was eliminated in the first round at the Ostrava Open after an dismal showing against Alycia Parks.
Daria Kasatkina was eliminated in the very first round of the US Open earlier this year by an unseeded Harriet Dart.
Gauff displayed a decent performance at the 2022 US Open, going as far as the last eight before being eliminated by Caroline Garcia.
Garcia is seeded seventh in San Diego and she will be hoping to go deep into the tournament, but her first test against home favourite Collins will be tricky.
Monday's first round of the 2022 San Diego Open will feature Veronika Kudermetova, the 12th-ranked player in the world, taking on Sloane Stephens, who is ranked 50.
The tournament will be held on an outdoor hard court at the Barnes Tennis Center, and the Dunlop Grand Prix Regular Duty ball will be used.
Brandon Nakashima and Daniel Galan will face each other in the first round of the 2022 ATP San Diego Open on Friday, September 23.
Giron comfortably defeated Argentinian Tomas Martin Etcheverry in the second round on Thursday by a score of 6-4, 6-3.
The Chilean was up against Steve Johnson in the first round and he recorded a comfortable 7-5, 6-2 win.