Czech Barbora Krejcikova on Sunday called for respect and professionalism in sports media as she hit out at "unprofessional" remarks made about her appearance during a broadcast on the Tennis Channel.

Wimbledon champion Krejcikova was competing at the WTA Finals in Riyadh this week, where she was beaten 6-3 7-5 by Olympic gold medallist Zheng Qinwen in the semi-finals.

During the Tennis Channel's coverage of the event on Friday, journalist Jon Wertheim, seemingly unaware that he was on air, made a comment about Krejcikova's forehead which was met with criticism on social media.

"As an athlete who has dedicated herself to this sport, it was disappointing to see this type of unprofessional commentary," world number 13 Krejcikova wrote in a post on X.

"This isn't the first time something like this is happening in (the) sports world. I've often chosen not to speak up, but I believe it's time to address the need for respect and professionalism in sports media.

"These moments distract from the true essence of sport and the dedication all athletes bring to the field. I love tennis deeply, and I want to see it represented in a way that honours the commitment we make to compete at this level."

Wertheim apologised for the comments in a post on X, saying: "During a Tennis Channel studio show on Friday, I made some deeply regrettable comments off-air.

"I acknowledge them. I apologise for them. I reached out immediately and apologised to the player... I realise: I am not the victim here. It was neither professional nor charitable nor reflective of the person I strive to be.

"I am accountable. I own this. I am sorry."

Reuters has contacted the Tennis Channel for comment.