It was a great day for the highly ranked Americans at the Guadalajara Open on Wednesday, headlined by world number five Jessica Pegula and her 2-6 6-3 7-6 (10-8) comeback win over Wimbledon champion Elena Rybakina.

Pegula, who is now locked into the top-eight and therefore will qualify for the WTA Finals, struggled to win points on her serve in the opening set, but raised her 57 per cent success rate up to 69 per cent in the second set, and 66 per cent in the decider.

The American had to come from a break down in the second set to keep her tournament alive, and she will now face Canada's Bianca Andreescu in the third round.

Meanwhile, fellow United States star Coco Gauff was too good for Italy's Elisabetta Cocciaretto, winning 7-6 (7-1) 6-3 to book a third-round clash with another Italian, Martina Trevisan, who earned her way there with a 6-0 4-6 6-3 win over Katerina Siniakova.

The other two seeded Americans were also successful, with 13th seed Madison Keys coming from a set down to defeat Ajla Tomljanovic 3-6 6-4 6-3, and 14th seed Danielle Collins repelled the challenge of Magdalena Frech 6-3 6-4.

There were positive signs for former world number five Eugenie Bouchard, who ended up losing, but showed she still has her talent by taking a set off world number 23 Jelena Ostapenko in a 7-5 2-6 6-1 result.

Russian pair Anna Kalinskaya and Liudmila Samsonova both emerged in three-set outings, with Kalinskaya outlasting Elise Mertens 6-4 0-6 7-5, while Samsonova upset world number four Aryna Sabalenka 6-4 2-6 6-2.

World number 12 Veronika Kudermetova kept her WTA Finals hopes alive with a 6-4 7-5 win over Donna Vekic, and the Czech Republic's Marie Bouzkova ousted Colombia's Camila Osorio 6-3 6-1.

In the late window, Sloane Stephens eliminated Olympic gold medalist Belinda Bencic 6-4 6-4, and top overall seed Paula Badosa retired due to injury after losing the first set 6-2 against Victoria Azarenka.