Venus Williams upsets World No 16 Veronika Kudermetova in Cincinnati

Williams, 43, defeated the world number 16 6-4 7-5 to progress to the second round of the Western and Southern Open.

The world number 533's last top 20 victim was Kiki Bertens, who Williams overcame at the same tournament in 2019.

"Definitely satisfaction from today is [from] all the work that goes into just being here at all," Williams said, after her win.

"I did my best to be here as soon as possible in the best form possible I could bring in that amount of time. So that makes it satisfying, to be able to get a win with very little time to prepare."

Meanwhile, Caroline Wozniacki will continue her return from a three-year absence in an opening round clash with lucky loser Varvara Gracheva, after Elina Svitolina withdrew from the tournament due to a foot injury.

In the men's draw, Dan Evans' opening match in Cincinnati was among the fixtures to be delayed after rain wreaked havoc on the opening round of the Western and Southern Open.

The British number two was scheduled to play Italy's Lorenzo Musetti in his first round match on Monday, but was ultimately unable to take the court.

The match is among a host of fixtures to be rescheduled for Tuesday, with only five matches able to be completed on day two of the tournament.

Some first-round matches that were completed saw Canada's Felix Auger-Aliassime overcame Italy's Matteo Berrettini 4-6 6-2 6-3, while Chilean Nicolas Jarry also came back from a set down to beat Roman Safiullin.

Dusan Lajovic, Emil Ruusuvuori and Jordan Thompson all progressed through to the second round with straight-set wins.

READ MORE: Novak Djokovic on Wimbledon final loss: I was over it in a day