Tennis commentator Andrew Castle is facing heavy criticism after making a snide remark about Serena Williams during Roger Federer's shock ATP Finals defeat to Kei Nishikori in London.
Nishikori won in straight sets 7-6(4) 6-3 to record just his third win over Federer in 10 matches, and his first since 2014.
Federer, who has won the year-end event an unprecedented six times, was off his game from the outset and angrily hit a ball into the crowd after a Nishikori winner.
In rare scenes, the chair umpire hit Federer with a code violation.
MORE: Barty heads Newcombe Medal shortlist | Federer in shock loss to Nishikori
In the commentary box, Castle referenced Williams' US Open outburst when speaking of Federer's own struggles.
"I don't think we will see a Serena Williams meltdown and call him a liar and a thief," he said.
The comments were met with shock on social media, with many viewers wondering why he would bring it up.
Andrew Castle is disgusting. He says - "I don't think we will see a Serena Williams meltdown yet and call him a liar and a thief", right after Federer got a coding violation and hit a ball into the crowd. @all_serena
— Qai Qai’s Protective Services 👶🏽 (@serenaw_23) November 11, 2018
Andrew Castle is so bad. #ATPWorldTourFinals
— Neil (@tothabrink) November 11, 2018
That's just bad from Andrew Castle, Federer gets a cold violation for hitting the ball into the crowd. He says - "I don't think we will see a Serena Williams meltdown yet and call him a liar and a thief" That is very poor.
— Iain Fordyce (@IainFordyce) November 11, 2018
@bbctennis Andrew Castle’s comment in commentary of the ATP Finals about a @serenawilliams style melt down is so out of order & utterly sexist!!!
— Alicia Mac Mahon (@aliciamacm) November 11, 2018
Andrew Castle having a dig at Serena on tv now- and you are? Stupid little man who managed to get a nice tv career despite not being able to hit a ball! #bbctennis #andrewcastle #serenawilliams #ATPWorldTourFinals
— Peter Ustinov (@VaughanLJ) November 11, 2018
What have we done to deserve Andrew Castle’s commentary? I honestly don’t understand how this man is employed #ATPFinals
— Yinka Olutola (@95_yinka) November 11, 2018
Was there any need for Andrew Castle to bring up the Serena incident in response to a warning for Federer?
— E R J (@ILoveSport356) November 11, 2018
Castle's comments were in relation to Williams' US Open final outburst when she had a run-in with chair umpire Carlos Ramos during her defeat to Naomi Osaka.
The incident sparked global headlines and weeks of debate after Williams called Ramos a "liar" and a "thief" after she was hit with a code violation, a point penalty and a game penalty on the way to a 6-2 6-4 loss.
Last week, Federer weighed-in on the outburst, saying Williams "should have walked away" and that her actions "went too far."
Castle retired from professional tennis in 1992 and has been commentating for over 20-years.
He reached one ATP Singles title and had a career-high ranking of 80 in 1988.
