Nadal splits the two men in red with a cracking overhead to get Europe up and running again, but another composed Tiafoe backhand levels it up.

Ooooh, but after a European point, a Tiafoe double fault brings up two break points!

Real pressure now. On second serve, Tiafoe is called for a double hit and Europe have the break!

Tiafoe isn't happy about that - neither is Team World captain John McEnroe.

Tiafoe, playing well, catches a forehand out of the middle to move World 15-30 up but a Sock miss offers Europe momentary reprieve.

Federer holds firm on serve, however, and it's a European hold.

The tension's ramping up out there!

Image source, Getty Images

An entertaining rally ends with Nadal scampering off court and he sends a forehand around the post, but it's wide!

Tiafoe runs around the net to acknowledge the Spaniard's attempt.

Great stuff.

No! At 30-40, a Federer forehand looks as though it may earn the break but it goes wide and we're back to deuce.

Nadal looked like he wanted that one.

However, an unforced error from Sock gives Federer and Nadal another chance, but a wild attempt at a forehand down the line from the Swiss brings us deuce again.

Tiafoe then goes cross-court before a delicious Sock drop shot completes an impressive hold.

Good spell this for the American duo.

Two all-time greats aren't going to lie down and they quickly move 0-30 up as they look to get the break back.

And while World fight back, Sock nets a baseline forehand.

Two break points for Europe!

Oooooh, a Nadal miss followed by a stunning Tiafoe return bags three break points for Team World.

Up steps Rafa though with a backhand that sails past Tiafoe and the Spaniard says "have some of that" as he follows it up with an ace.

Two saved, but a volley from Federer at the net goes deep and World have the break!

Groans from the crowd...

Image source, Getty Images

Despite a Team Europe winner that nearly takes the roof off, Tiafoe and Sock hold and avoid going on the backfoot early in the second.

Jonathan Jurejko
BBC Sport at the O2 Arena

London has turned into New York.

Banging tunes and the dance cam are in full swing.

Not quite the same reception from the British crowd as we see during the US Open though.

Stiff upper lip, etc.

Federer on serve for set two and the Swiss maestro swings into action to win the game without any problems. Always had a very handy serve has Rog.

Image source, Getty Images

Break point Europe - more importantly, a set point!

And they get it as Sock nets a backhand!

Federer and Nadal skip towards their team-mates as a big cheer rings out around the arena.

Job half-done.

Image source, Getty Images

Ooof, some BIG serving from Tiafoe puts World 40-15 up but a classy cross-court spinner from Nadal keeps the boys in blue in it.

And then a miss from Sock at the net brings us to deuce...

Fine end to the game from Federer and on we go!

That was looking hairy for a second but Fedal came through their first big test of the evening.

Nadal, back on serve, wins a couple of quick points but a miscued Feder backhand at the net brings it back to 30-15.

Ooooh, a big return from Jack Sock finds the gap left by Federer before another World point brings up the first break point of the night!

Sock can only sky his return, though, and Federer smashes his way to an important point.

Deuce.

A well-played overhead forehand from Tiafoe brings he and Sock to 40-15 and then the former pops up with a clinical backhand at the net for another hold.

Jonathan Jurejko
BBC Sport at the O2 Arena

"Let's go Roger, let's go!"

The packed arena breaks out into its first Federer chant of the evening.

That's shortly after Federer gets a marriage proposal from a fan.

Not sure Mirka - who I've not spotted here yet - would be on board with that.

Image source, PA Media

Hmmm, a Federer forehand sails into the net. 40-30.

And there's that strategy again - both players hammer shots at Tiafoe at the net and, despite the American's best efforts, the game goes to Europe.

There's a clear strategy from Federer/Nadal to target Tiafoe at the net.

It's been working so far.

A misjudged volley at the net from Nadal, however, moves World to the cusp of a hold - and they do so after successfully challenging an 'in' call.

Three games apiece. Who's going to blink first?

Jonathan Jurejko
BBC Sport at the O2 Arena

Eeek!

A tear-jerking moment at the changeover as the big screen shows a tribute video to Federer featuring his mum, Nadal and South Africa rugby union captain Siya Kolisi.

If they carry on with those after every two games there won't be a dry eye in the house.

And Federer won't be able to play because he'll be in bits.

Quick hands allow Federer to swipe a forehand away and it takes Europe to 40-15.

Then a well-placed Federer backhand forces Sock to go long!

It's all going smoothly enough so far.

Image source, Getty Images