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 the hard fight for equality, 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, who reached the US Open quarter-finals for a third successive year with a 6-7, 6-1, 6-4, 6-4 win over Uzbekistan's Denis Istomin on Tuesday, does not agree, though. "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.
Third seed Murray set up a clash against Stanislas Wawrinka, the ninth-seeded Swiss, who put out Czech fifth seed Tomas Berdych.
Wawrinka into last eight
The Swissman beat Berdych 3-6, 6-1, 7-6, 6-2 in two hours and 47 minutes on Louis Armstrong Stadium.
Wawrinka, who has had to live in the shadow of compatriot Roger Federer back home, was blown off the court by Berdych in the first set, but in a match featuring superb ball striking and a combined 68 winners, Wawrinka's consistency proved the difference against the fifth-seeded Czech.
He closed out the match by breaking Berdych's serve for the sixth time to move into a quarter-final against Andy Murray, Britain's defending champion, or Russia's Denis Istomin.
"It's always tough to play against Tomas," Wawrinka said.
"He always puts you under pressure. I'm just really, really happy. Tonight is a night I will never forget."
Djokovic defends Federer
Federer suffered a stunning US Open fourth round straight-sets upset at the hands of Spanish 19th seed Tommy Robredo on Monday.
It is the first year since 2002 that the 32 year old has not made a grand slam final and sparked feverish speculation over his future in the sport with the loss to Robredo coming on the heels of a second-round exit at Wimbledon.
"Roger did not play close to his maximum level so it's always a question of why is he not playing well. People need to give him a break a little bit, because I think it's normal to expect that he's not moving as well as he did when he was No. 1 and he was so dominant," said the Serb.
"For me, he's still playing really well and definitely deserves to be one of the top five players in the world, no question about it."
Djokovic said he would not be advising Federer on what his future plans should be despite his rival having slipped to No 7 in the world, his lowest ranking for over a decade.
"How long he's going to play? That's a question for him. But he's what, 31, 32 years old? Tommy Haas is 35 and close to the top 10.
"So I think people are seeing Roger always being a top three, top two guy and competing for grand slam titles. That's not happening, and all of a sudden it's a huge surprise."
Top-seeded Djokovic strung together 13 straight games to close out a 6-3, 6-0, 6-0 thrashing of Marcel Granollers and advance to his 18th straight grand slam quarter-final.
Hewitt loses to Youzhny
Lleyton Hewitt's five-set loss to Russian Mikhail Youzhny on Tuesday still stung, but the Australian veteran said having his family around him lessened the pain of defeat and helped him get his priorities right.
Hewitt's wife, Australian actress Bec Cartwright, and his three children were all at Flushing Meadows during his magical run to the fourth round.
After losing to Youzhny 6-3, 3-6, 6-7, 6-4, 7-5 on Louis Armstrong Stadium, Hewitt said defeats had become easier to stomach since he became a father to seven-year-old Mia, four-year-old Cruz and two-year-old Ava.
"Every loss still hurts, but it puts everything in perspective," he said. "Your priorities have changed.
"I still get in and prepare for matches as well as possible, but obviously you don't dwell on matches quite as much because you have other things to worry about."
Hewitt led 4-1 in the fourth set and 5-2 in the fifth before letting Youzhny off the hook. He said the physical exertion required to beat Argentina's sixth seed Juan Martin Del Potro in the second round two was still taking a toll.
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