Melbourne, Australia, 12 February 2020 | AAP /

Ajla Tomljanovic will play Anastasia Potapova for a place in the St Petersburg quarterfinals after a come-from-behind victory over Marketa Vondrousova on Tuesday.

Tomljanovic defeated the fifth seed 3-6 6-3 6-4 at the WTA Premier-level event to ensure she remains unbeaten in first-round matches in 2020.

Vondrousova, last years French Open finalist who fell to Ash Barty in the title match in Paris, is the world No.17 — the highest-ranked player Tomljanovic has beaten this year.

World No.57 Tomljanovic has never before played Potapova.

Meanwhile, fellow Australian Jordan Thompson defeated Croatian veteran Ivo Karlovic in straight sets in their first-round encounter at the ATP Tour’s New York Open.

One break of serve was enough for Thompson to seal a place in the second round at the indoor hard-court tournament.

World No.63 Thompson proved too consistent for the big-serving Karlovic and won through 6-3 7-6 (7-2).

A solid serving performance, which included six aces, helped Thompson keep his 40-year-old opponent at bay.

Next up for the Sydneysider is another big-serving challenge in American top seed John Isner.