Laughs from the crowd at a bit of a communication breakdown in the Fedal team.

They're a bit rusty. I can't blame them.

Spain's US Open champion is gripped:

Nadal's caught too close to the net and he fails to connect meaningfully with a thunderous Jack Sock forehand.

Federer then cracks a wry smile as he fails to reach the bouncing ball.

Nadal nets from the baseline and it's a solid hold from Team World.

Jonathan Jurejko
BBC Sport at the O2 Arena

Fedal have the mischievous looks of a pair of schoolboys who have 50p worth of penny chews in the bag but have only paid for 20.

A few pantomime boos when Tiafoe, Sock and McEnroe contest it.

Then replays show the ball did go through the corner of the net.

Cue laughter.

What's this?!

Federer races to send a forehand down the line and it goes through the hole in the corner of the net!

After all these years, still doing remarkable things. 40-15.

World bring it back to 40-30 but an unreturnable Federer serve gives Europe the game.

Image source, PA Media

Frances Tiafoe, still relatively fresh from his run to the US Open semi-finals, to serve, but at 30-0 up he sends a forehand long.

But a wide volley at the net from Nadal gives the American duo the chance to level and they do just that courtesy of a Tiafoe ace.

Jonathan Jurejko
BBC Sport at the O2 Arena

Fun, not funereal, was how Roger Federer wants tonight to be.

And he's certainly enjoying being back on court.

A beaming smile as wide as the nearby Thames is planted across his face after virtually every point.

An early challenge from Team World and it's indeed overturned - Rafa Nadal's second serve was incorrectly called in.

And Federer wins his first point with a nicely-taken volley that zips past Jack Sock!

A big cheer, and then another as Nadal slams a volley down.

Two more quick points and Fedal are on the board early!

Hope Rafael Nadal has got some energy left after supporting Andy Murray through that blockbuster of a singles match.

Image source, Getty Images

"Looking forward to it guys," says Roger as he leaves his team-mates and walks back on to the court.

Europe won the toss and have elected to serve first.

Image source, Getty Images

Jonathan Jurejko
BBC Sport at the O2 Arena

Fans have also come from far and wide.

Roger Federer is an international phenom and there has rarely - if ever - been any other tennis player who has attracted such fandom.

Switzerland. Poland. Japan. Thailand. United States. Greece.

There is a world buffet of Federer fans here.

Jonathan Jurejko
BBC Sport at the O2 Arena

Image source, BBC Sport

Federer caps. RF tracky tops. A homemade Swiss-coloured banner. It's easy to see why the Springer family caught my eye at the O2 Arena.

Roger Federer has inspired devotion like few other tennis players, which is perfectly illustrated by dad Robert, mum Agnieszka and their teenage son Jacob.

The family have travelled from the Polish city of Wroclaw to see their hero for one final time.

"We are in a Royal city and Roger is the King of Tennis. He's the one and only," says Robert.

Not only have the family watched Federer at tournaments, they have also managed to meet him and get lots of signed memorabilia.

Image source, Robert Springer

"I have liked tennis since I was a child - I liked Pete Sampras and Boris Becker - but Roger is a special, higher level," adds Robert.

"He has quality, empathy, a super sportsman, a gentleman and a good father.

"And he always has time for his fans."

Image source, Robert Springer

Federer and Nadal walk out on court to rapturous applause, as you'd expect.

It's been a long wait but they look ready to go.

Jonathan Jurejko
BBC Sport at the O2 Arena

Someone call the cops. The DJ is playing a woeful remix of Oasis classic Wonderwall.

Even that can't dampen the mood.

Cheers as Team Europe's non-playing members walk out, with a heartbeat pumping loudly to crack up the atmos.

My heart is pounding. Imagine how many BPM Roger's ticker is going.

Here we go...

Image source, Getty Images

Roger Federer and Rafael Nadal have faced each other 40 times over the years. Nine of those matches were Grand Slam finals.

Nadal holds a 24-16 record over his long-time rival, but tonight they are on the same side as they set out to earn a point for Team Europe.

At a news conference on Thursday, Federer spoke about teaming up with Nadal for his farewell match.

"Of course, it's super special playing with Rafa," he said.

"Feels really different, you know.

"Also just walking out on court and having the chance to play with the likes of Rafa or Novak also in the past has been an amazing experience for me.

"So to be able to do that one more time, I'm sure it's going to be wonderful. I will try my very best. I hope to be good out there, and of course I will enjoy it but it will be hard."

The Sports Desk

The latest edition of The Sports Desk podcast features a fascinating interview with Marc Rosset, the Swiss 1992 Olympic gold medallist, who beat Roger Federer in Federer's first final at the 2000 Marseille Open.

As Federer's Davis Cup team-mate and friend, Rosset was able to offer plenty of insight into his fellow countryman.

On a youthful Federer's short temper: "When he was a kid, I remember one story when he was in the national centre and he behaved so badly that the next day, at eight o’clock, he had to clean all the courts as a punishment.

"And I think that’s why I loved him immediately when I saw him, because he had this temper. He was a cool guy, he liked to have fun so we matched immediately when I saw him as a human being.

On Federer being emotional in victory: "Even if he was winning Wimbledon or other tournaments, many times you saw him after the victory crying because he was holding all this pressure and feelings inside him. He didn’t want to show anyone but once a tournament was done, he was very emotional."

Subscribe to The Sports Desk podcast and listen to the full interview on BBC Sounds.

Russell Fuller
BBC tennis correspondent

We will, of course, remember those 20 Grand Slam titles, and those 237 weeks in a row as the world number one.

We will also remember Federer for his movement, his forehand and his serve.

But he will be remembered most of all for the elegance with which he played the sport he loved: a style and grace which endeared him to so many.

We had been dreaming of the prospect of Federer making a comeback at the age of 41.

Illogical, probably, after four knee operations. But such mesmeric gifts leave little room for logic.

Wimbledon, or his home town of Basel - where, as a ballboy, his passion for professional tennis was stirred - would have been perfect places to say farewell.

But at least in London he will have the company of Rafael Nadal, Novak Djokovic and Andy Murray: rivalries that have further enriched his career.

Jonathan Jurejko
BBC Sport at the O2 Arena

"About seven minutes to go until the one you're all waiting for," says the MC.

For those of you at home that means time to make a quick cuppa.

For those here it might mean a trip to the loo. Not sure how quick that would be, judging by the queue I saw on the way in.

Probably not worth risking missing the start, IMO.