Andy Murray believes women should play best-of-five-set matches to justify equal prize money at the grand slams.

Although there seems no prospect of any of the slams taking a step back after making the changes in pay, it is an issue that continues to rumble on.

It hit the headlines last year at Wimbledon when French player Gilles Simon argued the women's game was not as entertaining as the men's, and he added: "It's not only my point of view, it's the point of view of everybody in the locker room."

Murray does not think it is about entertainment but about fairness, and for him that means women playing the same format as men.

Talking to the New York Times, the Scot said: "It isn't about it being inferior. As I see them, they're two different sports.

"It's not like at the 100 metres at the Olympics, not because they're not running the same speed as the men. It's just because we play five sets.

"I'm not saying the men work harder than the women, but if you have to train to play five sets, it's a longer distance. It's like someone training to be a 400m runner and someone training to be a 600m runner.

"I think the women should play best-of-five sets. I don't see why they couldn't do it. It would mean the days in the slams are a little bit longer. And maybe it doesn't have to be from the first rounds.

"I think either the men go three sets or the women go five sets. I think that's more what the guys tend to complain about, rather than the equal prize money itself."

There is another debate about whether the men's game is now too physically punishing.

The US Open, where defending champion Murray was due to play his fourth-round match against Denis Istomin on Tuesday night, is the only one of the slams that features a tie-break in the fifth set.

A lot of people think that should be the norm, while there is another group, including Martina Navratilova, who believe the men would be better off playing best-of-three sets, as they do at every other tournament during the year aside from Davis Cup.

Murray does not agree, though, saying: "I've always played five sets at the slams. It's what makes them different. I would rather want the five-set rule for the men and the women.

"They did it before. They used to do it in finals, I think in the Tour finals, and some of the big finals on the WTA Tour. So it's not like women cannot play five sets.

"Steffi Graf and Navratilova and those players were unbelievable over five sets, and in great shape. So it's not that, that isn't the issue."

The final of the end-of-season WTA Tour Championships was a best-of-five set match between 1984 and 1998 before reverting to best-of-three.

Only three matches went the distance, with Monica Seles beating Gabriela Sabatini in 1990 and Graf winning five-setters in 1995 and 1996.