Billie Jean King says grand slam tournaments should reduce men's matches to best-of-three sets to maintain the appeal of tennis to modern consumers.

The American has been a decades-long pioneer of equality within the sport in which she was a 12-time grand slam singles champion, collecting six of her haul at Wimbledon.

Now she believes men should be playing shorter matches at the majors, to ensure matches remain sufficiently bite-sized for audiences.

Speaking on Thursday at the WTA Finals Singapore launch, King found herself in a familiar debate about whether women should play matches of the same length as the men, who play best-of-five singles contests in all the grand slams.

Rather than advocate female players switching to best-of-five matches, King said: "Personally, I don't want the men playing five sets anymore.

"I think it takes too much out of them. I want them to play as long as possible (in their careers)."

The founder of the Women's Tennis Association, which runs the women's professional tour, added: "I think especially with technology and concentration spans, kids can last about seven seconds now. The point is, I think people want quality over quality."

King said at the launch event, streamed on the tournament's Facebook page, that women were willing to play best-of-five matches if asked but that those in charge "only want us to play two out of three".