Ajla Tomljanovic missed the opportunity to reach the St Petersburg quarterfinals after being beaten in straight sets by Russian teenager Anastasia Potapova.
Tomljanovic, who fought back from a set down to win her opening match over fifth-seeded Marketa Vondrousova, was unable to build on that victory as she succumbed 7-6 (7-2) 6-3 to a player ranked 44 spots below her on Wednesday.
Johanna Konta's search for a first victory since the US Open goes on after she was beaten by 159th-ranked Oceane Dodin in the second round.
The British No.1, ranked 14, has now lost all three matches she has contested in 2020 having gone out in the opening round of the Brisbane International and the Australian Open.
She chose to miss Great Britain's Fed Cup play-off against Slovakia, instead taking a wild card into the WTA tournament in Russia, where she received a first-round bye as the fourth seed.
But Konta's lack of matches again showed as she was beaten 6-3 6-4 by big-hitting qualifier Dodin.
France's Alize Cornet overcame former Roland Garros champion Jelena Ostapenko 6-1 6-2 to book her place in the second round.