Another double fault for Dimitrov, seven now (SEVEN). It gives Roger Federer a break point and he doesn't waste those.

It's a concession to be honest, overhit from Dimitrov and that could be curtains in this set.

Image source, Getty Images

Ooh! Props to the lady in the crowd who has just been thwacked on the leg by a shank from Nadal. She grinned it off. That'll leave a fair old bruise.

Gilles Muller isn't giving up that easily. He hammers through his service game for a love hold. Nadal still has the break.

Image source, Getty Images

Roger Federer's tempo on serve is something else, he takes games away from you before you've got your breath back from the last one.

That's six games of this set done, with breaks, in 20 minutes.

Jamie Baker
Former GB Davis Cup player on BBC Two

This has turned into such a fantastic contest, especially on the Muller service game. It's a real tactical challenge.

What a fightback this has been from Rafa Nadal.

He's made of stern stuff. Now he's the one giving Muller the run around, slapping forehands and backhands around for fun to hold his serve.

Dimitrov is the master of his own demise as some cheap shots get away from him and Roger Federer cashes them in. That's a break and Roger will already be eyeing up the second set.

Image source, Getty Images

Fancy asking Boris Becker a few questions?

Now's your chance...

'Desperate defending' from Rafael Nadal in his match against Gilles Muller as he manages an impressive lob over his opponent.

Advantage Nadal, and a furious swipe of the racquet from Muller as he overhits.

On one leg from Muller, trying to swipe cross-court - and he nets! Nadal has the break!

First break point: saved.

Second break point: saved.

Third break point: saved.

As you were...

Image source, Getty Images

A nice disguise from Nadal, charging up to the net before walloping a winner back.

Double fault from Muller now, the pressure just starting to tell, and a smash from Nadal brings up three break points!

He had two break points on the last Muller serve but his opponent saved them - can Mulller do the same again?

* denotes next server

Shot Dimitrov! Two in fact, two of those one-handed sweeping backhands that Bevo was telling us about. In to the net now to volley home and that's 40-15.

Another good hold.

Nadal fires through his service game, combining big serves with a lovely, curling winner, and that's an easy hold for the fourth seed.

Who will blink first?

Comedian Greg Davies on Centre Court with the Radio 5 live team: "I don't play tennis obviously but I enjoy watching athletes at work. It's amazing to be this close to Roger Federer.

"The last time I was here 10 years ago I was doing some advertising for cricket and I came to Centre Court dressed as WG Grace, with a cricket bat, and was shouting out cricket slogans. Everyone thought I was a nutter.

"This is a much happier occasion for me."

Chris Bevan
BBC Sport at Wimbledon

I spoke to Grigor Dimitrov at the end of 2010, when he was the new kid on the block - the highest ranked male teenager on the tour, who was about to break the top 100 and was seen as heir apparent to the man across the net from him right now.

Dimitrov was known as 'Baby Fed' in those days, because of the similarities in their playing style, notably that sweeping single-handed backhand they both share. "I loved watching Roger when I was growing up and I still watch him when I can, no matter what because you can learn so much," Dimitrov told me back then.

He won't get a better view of Fed than the one he has at the moment, but he is not a baby anymore and is probably a bit fed up of getting taught a lesson by his hero - he has lost all five of their meetings since they first played each other in 2013 and has got a lot of work to do to if he wants to improve on that record today.

Dimitrov didn't do much wrong in that first set, he hit more winners (10) than Federer (8) but a few errors at key points proved costly. Dealing with pressure is often what separates the best.

He holds his serve first up though.

Federer is flying through his service games though, no time at all.

Serve and volley from Muller has Nadal on the run, and Muller doesn't miss a beat to snag the advantage.

There's the serve out wide, Nadal slaps home a return - and Muller is perfectly placed for the volleyed winner. Just a shade under seven minutes, and Muller has held his serve.

Nadal gesticulates as his cross-court forehand finds the net. Not a happy bunny with that shot.

That's one way to keep this game going, though - a stunning forehand from Nadal, deep and wide on the left side of the court, and it throws Muller completely off-balance.

Muller restores his advantage with an ace out wide, but then a little backhand plonk at the net spins just wide! Third deuce, here we come...

John McEnroe
Three-time Wimbledon singles champion on BBC TV

Federer has just got an uncanny sense of knowing when the other guys' going to blink. When to move forwards, when to bide his time. All these qualities, if you add them all up - his forehand is one of the best shots ever, his backhand's got way better, he moves better at 35 than 27, he's served 10,000 aces...

I could go on.

Nadal is at full stretch, picking up a ball from on the baseline and lobbing it up and over Muller for a wicked winner.

The Spaniard is still fiddling around with that right ankle but hes gifted another point as Muller takes a hop and a swipe - and misses a simple forehand return!

Another good return from Nadal wrong-foots Muller and that brings up two break points. Muller saves the first with a glorious drop shot, and then Nadal goes long. Deuce!