Did you know men and women use different balls when playing professional tennis?

Some of the court staff at the Cincinnati Masters clearly didn’t after Aussie Nick Kyrgios began his second round match-up with Alexandr Dolgopolov using the wrong balls.

The difference in the balls is minimal but those used by men feature “extra-duty felt” which slows them down, while women use the regular variety.

The women’s balls also feature a different logo, something noticed by Dolgopolov after six points of the match that Kyrgios ultimately won 6-3 7-6 (8-6).

When the Ukrainian raised the alarm, spotting the distinctive red marks on the women’s tennis balls, Kyrgios also caught on, before expressing his bemusement.

“What are you guys doing?” he said.

“Christ almighty.”

Kyrgios was struggling in the early stages, trailing 3-1, but won the next five games to take the opening set in style.

The 22-year-old, still troubled by a persistent hip injury, hit 20 winners in the victory.

And he also served well, smashing 15 aces and winning 84 per cent of points on first serve, helping him edge what was a tight second set.

Dolgopolov was far from his best, hitting 36 unforced errors in the contest, which took one hour and 26 minutes to complete.

Kyrgios will now play Ivo Karlovic in the third round at the ATP 1000 event and the Canberran has a good track record against the huge-serving Croatian, winning all three of their clashes.

There was more good news for Aussie tennis ahead of the upcoming US Open when Ashleigh Barty surprised Venus Williams in three sets at the same tournament.

Barty, ranked 48th in the world, upset World No.9 Venus Williams 6-3 2-6 6-2 to book a spot in the event’s third round.

“It feels really good. To play Venus on such a big stage is a privilege for me and to play as well as I did, I’m really excited,” Barty said afterwards.

“She’s a genuine champion of the game and paved the way for us young players coming through.”

The win was Barty’s first against a top-10 player on tour and Williams said afterwards that Barty “just played really well”.

Barty is set to replace Samantha Stosur as the our second-ranked women’s player after her win, which is likely to see her rise to at least 42nd in the world when the rankings are next updated.

Australia’s top-ranked female, Daria Gavrilova, lost in three sets to Italian Camila Giorgi in Cincinnati.