Goodness me. What a rally that was. Pinging back and forth at the net before an instinctual forehand whizzes past Djokovic and brings up a break-back point for the Spaniard.

Seven unforced errors already from Alcaraz in set two.

He moves to 15-30 on the Djokovic serve though.

Image source, Getty Images

Image source, Getty Images

Woah. A wild Alcaraz shot flies out of the court for 30-15.

Djokovic berates himself as a lengthy rally ends in him firing into the net.

Alcaraz wraps up the hold with a 109mph serve. The Spaniard is finally on the board in set two.

Night and day from the first set for Djokovic.

The crowd are well behind him now too.

A volley at the net and a big serve hand Djokovic a hold to love. What a start to this set for the Serb.

Three games in and Alcaraz is yet to get on the board.

Jonathan Jurejko
BBC Sport senior tennis reporter at Flushing Meadows

The bones might be aching, but the fire inside is still burning.

Djokovic roars and punches the air. He's back in this - and he knows it.

So do the crowd.

"Nole! Nole! Nole!" rings around Ashe.

And we have lift off!

Alcaraz fires long and Djokovic has the break of serve early in set two! Game on.

He raises a fist to his coaching box. That means a lot.

Well hello.

Djokovic brings up a break point. Alcaraz has only faced eight so far this tournament.

Annabel Croft
Former British number one on BBC Radio 5 Sports Extra and BBC Sounds

There is a bit more freedom with Djokovic in the way he has finished that game. He started to take control of the points, use the backhand down the line and came forward several times.

A sumptuous volley from Djokovic and he's back on track.

That's followed by a lovely forehand whipped down the line to seal the hold.

A big hold from 0-30, that.

Jonathan Jurejko
BBC Sport senior tennis reporter at Flushing Meadows

Image source, get

Father Time is tapping on Djokovic's shoulder, it seems.

The 38-year-old Serb is not far off Alcaraz, who has actually been poor by his standards - but not close enough.

Djokovic, unsurprisingly, is not quite as sharp as we remember him against the very best.

Can Djokovic get back into this?

Alcaraz goes for power and it pays off for a 0-30 lead.

He overcooks the forehand and that hands Djokovic the first point of set two behind his serve.

David Law
Commentator on BBC Radio 5 Sports Extra

I think that is one of the worst sets that Alcaraz has played at this Championships. Of course he is up against a better opponent, but he has got away with it.

There has been a lot of mistakes by his standards, the feel is not there yet

Image source, Getty Images

Alcaraz takes the set at the first opportunity with a big serve that Djokovic can only stick out a hopeful racquet at.

The Spaniard is well on top in this semi-final.

Djokovic drops to his haunches as he misses the forehand. He knows that was big.

Woops. Alcaraz winds up the forehand but slams it into the net. A rare miss. 30-30. Alcaraz needs two points for the set but two points for Djokovic would turn this set on it's head.

What a point. Both players chase down the drop shot but it's Djokovic who comes out on top as Alcaraz can't chip the ball back in from close to the net. 15-15.

Well that's about as straightforward as it has been for Djokovic, he takes the hold to 15.

But now he'll have to do something he's not been able to do yet and that's break Alcaraz's serve.

The Spaniard will serve for the set.

Image source, Getty Images

David Law
Commentator on BBC Radio 5 Sports Extra

This has not been a 'classic' set as of yet. We have seen a few good exchanges and some great winners, but a lot of unforced errors and unusually inconsistent shots from both players too.

While every service game for Djokovic has been a struggle, it's been smooth sailing for Alcaraz by comparison.

He gets a hold to love on the board to put himself within one game of the first set.