Have the efforts of his last-round match taken too much out of Nishikori? Well, at least he has a game on the board now. He has had to work hard to secure it though, but that could be a big confidence boost for the Japanese player.

Skezzzaaaaaa:, external With the confidence from the last win Andy Murray should have an exciting match against Novak Djokovic.

Andrew Priestley:, external We're in for a long night, but with these quarter-final match-ups involving these great players, I don't think we'll get bored!

Let us know your thoughts on today's action, as well as your thoughts and predictions for the Andy Murray v Novak Djokovic match, which will be starting at about 02:00 BST.

Wawrinka's excellent start continues and this is already looking a tricky task for Nishikori. The third seed comfortably holds his serve in the third game. He leads 3-0 already.

Image source, Reuters

A cracking rally of 25 shots in only the second game when Wawrinka has a break point. Unfortunately for the Swiss, his last shot goes just long.

But it does not matter as Wawrinka has a second break point very quickly afterwards and this time takes the opportunity with a big forehand winner. A pump of the fist from the Australian Open champion and it is 2-0 to Wawrinka.

As always you can listen to live coverage on BBC Radio 5 live sports extra. Hit the play button at the top of this page or the live coverage tab for all the action.

Nishikori has an early chance to take control as he creates a break point in the first game of the opening set. But the third seed fights back to hold his serve, although it is an encouraging start for the Japanese player.

Route to the quarter-finals - Kei Nishikori (Japan, 10th seed)

Round one: Beat Wayne Odesnik (USA) 6-2 6-4 6-2

Round two: Beat Pablo Andujar (Spain) 6-4 6-1, Andujar retired

Round three: Beat Leonardo Mayer (Argentina, 23rd seed) 6-4 6-2 6-3

Last 16: Beat Milos Raonic (Canada, fifth seed) 4-6 7-6 (7-4) 6-7 (6-8) 7-5 6-4

Route to the quarter-finals - Stan Wawrinka (Switzerland, third seed)

Image source, AP

Round one: Beat Jiri Vesely (Czech Republic) 6-2 7-6 (8-6) 7-6 (7-3)

Round two: Beat Thomasz Bellucci (Brazil) 6-3 6-4 3-6 7-6 (7-1)

Round three: Beat Blaz Kavcic (Slovenia) walkover

Last 16: Beat Tommy Robredo (16) (Spain) 7-5 4-6 7-6 (9-7) 6-2

Piers Newbery
BBC Sport at Flushing Meadows

"Nishikori did not exactly leap out of his courtesy car and sprint in through the players' entrance when he arrived a few hours ago, not surprisingly bearing in mind his late/early finish on Tuesday.

"The Japanese player came into the tournament lacking match practice after the latest in a long line of injuries, but he has certainly had plenty of court time over the last 10 days - nine hours and 19 minutes to be precise, against Wawrinka's seven hours and 52 minutes. With the temperature currently around 31C, it could be a tough afternoon for Nishikori."

Nishikori's last 16 match against Raonic lasted four hours and 19 minutes in the Arthur Ashe Stadium, which concluded long after the other courts were quiet and all the food and souvenir vendors had pulled down their shutters. The Japanese player also needed treatment on a toe injury during the match.

"I was very happy to see a lot of people even at 2:00 in the night," said Nishikori after his win. "I don't even know how they go back home! I'm very happy to play like that."

But is he fit enough to play again so soon?

We've all had days at work when you have had to stay a few extra hours to make sure the job was done. But no one likes working until nearly 2.30 in the morning.

Image source, AP

It was all looking so easy for Kei Nishikori as he eased through the opening three matches, helped by the withdrawal of Spanish opponent Pablo Andujar in round two.

But things got a lot trickier in the last 16 on Tuesday as Nishikori battled through a five-set epic against Milos Raonic. The match ended at 2.26am, the joint latest finish in US Open history. Today he goes again.

Speaking of women's singles quarter-finals...

Image source, AP

Earlier today, Russia's Ekaterina Makarova moved into the semi-finals of a Grand Slam for the first time by beating Victoria Azarenka in the quarter-finals.

Makarova, 26, won the first set 6-4 against Azarenka, who had lost in the US Open final in both 2012 and 2013. But the 25-year-old Belarusian was not at her best and received a warning after smashing her racquet.

Image source, AFP

Makarova clinched the second set 6-2 to set up a semi-final against either Serena Williams or Flavia Pennetta.

So first up for us is the first quarter-final in the men's competition. Third seed Stan Wawrinka goes up against Kei Nishikori, who became the first Japanese man since Zenzo Shimidzu in 1922 to get to the last eight in New York.

In the women's competition we already know that China's Shuai Peng, who beat fourth seed Agnieszka Radwanska in the second round, will play 2009 finalist and former world number one Caroline Wozniacki in one semi-final.

But there is no doubting the best player in the female game at the moment. Serena Williams, with 17 Grand Slam singles wins already in a very packed trophy cabinet, has cruised through four matches and not dropped a set in the process. She faces Italian Flavia Pennetta, the 11th seed, in a match expected to start at midnight British time.

Hello, good evening and welcome to BBC Sport's live text coverage of day 10 of the US Open. We have the first two quarter-finals in the men's singles coming up, with Andy Murray expected to be on court against world number one Novak Djokovic at about 02:00 BST.

In between those matches, we also have Serena Williams in the women's quarter-finals, while a Briton could be soon playing in a final as Ross Hutchins is in mixed doubles semi-final action.

So make a strong coffee, bolt down the energy drinks and make sure you stay awake and stay with us. It is going to be a great night of tennis.

We have reached the quarter-finals stages of the men's and women's singles at Flushing Meadows and what a competition it has been.

Some have had to battle late into the night to fight their way through and make history.

Image source, AP

Others have found it much easier and are seemingly unstoppable.

Image source, AFP

British hopes are still alive as Andy Murray has produced some of his best form of the season.

Image source, AP

But now Murray faces the toughest task possible. Now he faces the best in the world.

Image source, Getty Images