NEW YORK -- After they advanced to the quarterfinals here, the Bryan Brothers were asked why the top men singles players don't play doubles.
"Best-of-five sets," Bob and Mike said, simultaneously.
The men's and women's US Open champions will each receive a sturdy $3 million check, but the men's winner will have run many more miles.
Last year, Serena Williams needed only 15 sets -- one more than the minimum -- to take the title over Victoria Azarenka. Williams played a total of 120 games, or 81 fewer than Rafael Nadal, who needed 201 games and 23 sets to earn the men's crown.
Gender equity is a beautiful thing -- not to mention the law -- but sometimes it's easy to lose sight of how hard these guys are competing.
Our most recent example was Monday night/Tuesday morning, when Kei Nishikori won an epic struggle over Milos Raonic, 4-6, 7-6 (4), 6-7 (6), 7-5, 6-4. The match ran 4 hours, 19 minutes -- and ended at 2:26 a.m. That tied the record for the latest finish ever at the US Open.
"I was happy to see a lot of people even 2 o'clock at night," Nishikori said afterward. "I don't even know how they go back home."
Said Raonic, "It was a combination of fatigue, pain in some ways, and just not feeling like I would expect or hope to feel late in a match."
The No. 10-seeded Kei Nishikori meets No. 3 Stan Wawrinka in the quarterfinals Wednesday. The other quarter from the top half of the draw? A few guys you may have heard of, Novak Djokovic versus Andy Murray. They know a little something about going deep; their 2012 US Open clash went 4 hours, 54 minutes, equaling the longest men's final ever here.
These cataclysmic collisions have the potential for some more five-set drama, which got our Baseline Buzz crew -- ESPN.com tennis editor Matt Wilansky and senior writer Greg Garber -- brainstorming over the infinite possibilities.
Greg Garber: The terrific thing about tennis is its what-have-you-done-for-me-lately approach to rankings and seedings. So when Murray fails to reach a final after winning Wimbledon last year, his ranking falls and -- boom! -- he's meeting Jo-Wilfried Tsonga in the fourth round of the US Open. And Djokovic in a ridiculous quarterfinal. With Roger Federer turning 33 and Rafael Nadal's career threatened by a series of injuries, Murray and Djokovic are the pair most likely to win Slams for the next few years.
Matt Wilansky: There was a time not so long ago when we exalted the Djokovic-Murray rivalry as the best in the game. But Murray's inconsistent results (he hasn't won a title since Wimbledon a year ago) have taken a little steam out of this matchup. Murray has looked sharp here, but he suffered cramps in his opener, and with the heat wave not abating for the next couple of days, it's a good thing they're scheduled to play at night. So far, Murray has run 6.09 miles in this tournament, while Djokovic just more than half that total, 3.63. And this doesn't bode well for the Scot, especially if this match comes down to attrition.
Greg Garber: I'm not so sure, Mr. Wilansky. When I saw those stats, it made me think Murray -- who trains in the oppressive heat of Miami -- is actually fit again after undergoing back surgery at the end of last season. He was consistently moving forward; Murray won a remarkable 28 of 31 points at net, which is something he needs to do against Djokovic, who holds a 12-8 head-to-head advantage. They split two major finals in 2013 (Australia and Wimbledon) and Djokovic beat him in straight sets in a Miami quarterfinal earlier this year.
Matt Wilansky: I don't discount Murray's bloody determination or his fitness. His workout regimen that often includes 400-meter repeats and Bikram yoga are impressive. But all things being equal, Djokovic has a tangible advantage. First, the obvious: The Serb has won four titles this year, which, according to the stats sheet, is four more than Murray. Secondly, Djokovic has been broken only four times in 52 service games. So to recap, the best returner in the game has served equally as well. Tough to crack that.
Greg Garber: The statistic that jumped out at me was the 0-for-7 against top 10 players since winning Wimbledon. Murray turned the corner by beating Tsonga in straight sets and that had to give him some confidence. Now, will Nishikori carry his newfound confidence (after reaching his second career major quarterfinal) into the match with Wawrinka -- or will he succumb to the fatigue that comes with finishing a long match so late?
Matt Wilansky: Perhaps this fun fact will shed some light: Of the four previous players who finished their matches after 2 a.m., all went on to -- you guessed it -- lose their very next match. And if that doesn't convince you, perhaps this photo that Nishikori posted of himself after his middle-of-the-night finish in the last round will. That said, I am a fan of Nishikori; he's as talented as anyone who plays this game, but I can't imagine he's going to be healthy enough to take out the Aussie Open champ Wawrinka. Even Wawrinka himself said that his career has been doomed by injury.
Greg Garber: Whoa, that is a killer number. All of them lost after staying up past their bedtimes. That is a tough recovery. So based on what you're saying, Wawrinka is a lock. That wouldn't be completely horrible, because it could deliver us a Djokovic-Wawrinka semifinal. I seem to remember a certain memorable marathon match in the quarterfinals at the Australian Open when Wawrinka surprisingly outlasted Djokovic 9-7 in the fifth and went on to win his first Grand Slam singles title.
Matt Wilansky: And a certain marathon here at the Open last year that went five sets and a certain Aussie Open round-of-16 clash, also last year, that ended 12-10 in the final set. Djokovic won both, but needless to say, these guys don't mess around against each other. So quarterfinal predictions, you ask: Djoker in four and Stan in three.
Greg Garber: Roger that. See you tomorrow.