Blink and you miss it.

Three aces in that game from Wawrinka which was just what the doctor ordered.

The crowd are fanning themselves in New York, it's still warm out there.

The more short points the better I'd say.

Image source, AFP

The Japanese player has started well here, crunching a forehand winner.

Commentators curse. A double fault follows but a very tidy point from Nishikori is won at the net to give him game point.

Another backhand error from Wawrinka and break is consolidated.

Image source, Reuters

Nishikori wins the longest point of the match so far as he scrambles around at the back of the court, retrieving the ball, before Wawrinka misses a simple volley.

A backhand error from Wawrinka gives Nishikori 15-40 and the first break point of the match. 

And another error from Stan! Just like that, after a routine start, Nishikori breaks and has the upper hand in this opener.

Nishikori's coming to the net behind his serve. He did that against Murray as well.

Little to report after another conventional hold.

Image source, AP

This is all too conventional, isn't it? 

Another simple hold of serve, none of the drama of our first semi-final so far.

A clash of styles this one. Wawrinka's big single-handed backhand against Nishikori's double hander. 

The Japanese player is electric around the court and the Swiss loves to hit a winner from nowhere.

Gael Monfils has been giving his view of the first semi-final to the media, explaining that it was Djokovic’s fast start which prompted him to adopt some unusual ‘slowball’ tactics. It’s fair to say the Frenchman robustly rejects the notion that he didn’t give his all.

“I think I tried my best,” he says.

“At the beginning I think Novak has been good, I didn’t serve great, it was very quick 5-0 and I got to change a little bit. That’s a little bit tough because for sure people aren’t ready to see that.

"But why would I stay 6-0 and not change anything? Definitely, I tried to get in his head and create something new for him to see.”

Image source, Getty Images

Nishikori in white, Wawrinka in red. 

The Swiss third seed hits a running passing shot past Nishikori at the net for 30-15 but Nishikori levels it up easy enough.

Easy as that.

Some big serves from Wawrinka and he takes the first game of this semi-final.

There's a lot of blue seats around Arthur Ashe stadium. The locals have nipped out for a breather after our first semi-final.

Judging by that first game, they shouldn't stay away for long.

Here we go then.

Stan Wawrinka to us underway for a place alongside Novak Djokovic in the US Open final.

Image source, Getty Images

Jeff Tarango
Former professional tennis player on 5 live sports extra

I am going to say whoever has the most backhand down-the-line winners will win the match.

I think it will come down to that important shot.

As Novak Djokovic said following his win earlier, the conditions are playing a big part today.

It is incredibly humid in New York and you'd think that would remain the case for at least the early stages of this one.

Who does that favour? I'm not sure. Wawrinka has had more time on court but Nishikori was taken the distance just 48 hours ago.

As I said this one looks closer.

Wawrinka leads the pair in terms of Grand Slam titles, with two wins to his name, but Nishikori has the better record at Flushing Meadows after reaching the final in 2014.

The Swiss player leads their head to head 3-2 but Nishikori beat Wawrinka en route to that final two years ago.

Nicely poised.

Image source, Getty Images

Admit it everyone. You had an Andy Murray Grand Slam semi-final penciled in for tonight at the start of the week.

It was not to be though as Japan’s Kei Nishikori came through their five-set thriller on Wednesday night.

Our semi-finalists have had it tough in the competition so far, both playing over 13 hours and Wawrinka even had to save a match point against Britain’s Dan Evans in round three.

Thanks Michael.

Well what did you make of that? One of the strangest tennis matches I have ever seen.

I can’t promise quite as much drama but this looks a close one on paper, right? 

The third seed against the sixth seed. It is Stan Wawrinka v Kei Nishikori.

It wasn't what we were expecting, and it had an unusual start but it turned into a good encounter of stamina, skill and desire with flashes of great tennis.

Novak Djokovic is into the final and can now rest. 

But, remember, we still have the second semi-final to come with Stan Wawrinka taking on Kei Nishikori. The man to guide you through that is Matt Henry.

Just like Gael Monfils, I'm off to lie down in a darkened room. Enjoy.

"Humid" is how Novak Djokovic describes his win over Gael Monfils in his post-match interview.

"I think that is all we were thinking about and feeling," he added. "The conditions were different from most of the days during the tournament but it was the same for both players.

"We expected it, heard it would be warm and humid and the number of you guys (the crowd) coming in made it even more electric and humid.

"I think at times in the tense moments we had exchanges from the baseline and Gael is one of the best athletes on tour. He is very entertaining to watch and he had a great tournament and I hope you all enjoyed our battle today."

Simon Cooper: Djokovic is a physical beast. Won Australia six times. OK, he's been injured. But guaranteed in potential fifth set he'd have been fine.

That is the seventh US Open final Novak Djokovic has now reached and he will play either Stan Wawrinka or Kei Nishikori in the match on Sunday.

He has won twice and lost four times in his previous US Open finals.

It also maintains an incredible record that has seen him only lose two Grand Slam matches since the start of 2015.

David Law
Radio 5 live sports extra commentator

That was one of the weirdest semi-finals we have ever seen.

Djokovic looks a little embarrassed because it was not particularly an exciting match but he is getting a huge ovation from this crowd.

Image source, AFP