Serena William's husband clapped back at her haters by wearing a t-shirt calling her the 'greatest athlete' as she cruised into the Australian Open semifinals

• Serena William's husband wore a t-shirt calling her the "greatest" as he watched her cruise into the Australian Open semifinals.
• Williams beat second seed Simona Halep in straight sets on Tuesday.
• The tee appeared to be a dig at the tennis boss who in January suggested Williams should retire because of her "age and weight."

Serena Williams has not only wowed fans with her tennis at this year's Australian Open, but also with her striking outfit.

However, on Tuesday, she was outdone in the fashion department by her husband Alexis Ohanian, who wore a t-shirt calling her the "greatest" while watching her cruise into the tournament's semifinals.

Williams brushed past second seed Simona Halep 6-3, 6-3 at the Rod Laver Arena to book her place in the last four, where she will face Naomi Osaka on Thursday.

Cheering from the sidelines, Ohanian's t-shirt featured an image of Williams and large red writing which read "Greatest Female Athlete."

The word "Female," however, was crossed out.

The tee appears to have been a dig at Ion Țiriac, the billionaire tennis boss who in January suggested Williams, 39, should retire because of her "age and weight."

Ohanian responded to Țiriac's comments at the time by calling him a "racist/sexist clown" - a sentiment he re-iterated after Williams' win over Halep.

"Good thing no one listens to that racist sexist [clown] Ion Țiriac," Ohanian tweeted in response to a tweet from the WTA congratulating Williams on her victory.

Ohanian's t-shirt could also be a reference to the debate sparked by Tom Brady winning his seventh Super Bowl about who should be considered the greatest in sporting history.

Brady, Williams, Michael Jordan, Simone Biles, LeBron James, Michael Phelps and many others have all been mentioned as possible GOATs in recent weeks.

This isn't the first time Ohanian has made a statement with his choice of attire during one of Williams' matches.

When Williams beat Maria Sharapova at the 2019 US Open, the Reddit co-founder wore a t-shirt promoting D.A.R.E - a Los Angeles organization that runs police officer-led classroom lessons in schools to help promote a drug-free life.

Sharapova had previously failed a drugs test during the 2016 Australian Open, testing positive for the banned substance meldonium.

She was originally banned for two years by the International Tennis Federation (ITF), however the ban was reduced to 15 months following an appeal at the Court of Arbitration for Sport (CAS).