Alex de Minaur takes on Dominic Thiem for the last spot in men's semi-finals at US Open 2020. AP
The battle of all mothers will be waged Wednesday at the US Open when Serena Williams faces unseeded Tsvetana Pironkova for a berth in the semi-finals.
Williams missed more than a year of competition when she had a daughter in 2017, and has since been seeking a record-tying 24th Major title. Pironkova is playing in her first tournament since she took a break of more than three years to have a son.
In another women's quarter-final match-up, World No 16 Elise Mertens will face unseeded Victoria Azarenka, who is also a mother. Azarenka has won nine consecutive matches, including the final in the Western & Southern Open that was played in New York as an in-the-bubble warm-up for the US Open.

Serena Williams takes on Tsvetana Pironkova in the first quarter-final of Wednesday. Images: AP
Two men's quarter-finals are also scheduled. No 2-seeded Dominic Thiem, a three-time Major runner-up, meets first-time Slam quarter-finalist Alex de Minaur, a 21-year-old Australian. No 3 Daniil Medvedev, last year's Open runner-up, plays No 10 Andrey Rublev.
The path to the men's title is wide open after overwhelming favorite Novak Djokovic was disqualified on Sunday for unintentionally hitting a line judge in the throat with a ball. Each of the men's quarter-finalists is seeking his first Grand Slam title.
(With inputs from The Associated Press)