Murray is just not there at the moment. Six games in a row for Wawrinka now and the Scot has put up very little fight.

Wawrinka breezes to 40-15 and wins the game by showing lovely touch at the net.

Make that seven games in a row. Time to panic?

Pat Cash
Former Wimbledon champion on BBC Radio's online-only commentary

Murray is reasonably calm about this at the moment - which is slightly concerning.

Luke Davies: This is a huge set psychologically. Win this and win the match IMO

Image source, Reuters

Wide goes Murray.

That was a very untidy game. Not the start he was after. Andy is going to have to come from behind in this set.

Murray has hit three more unforced errors than winners today and the Scot adds two more to that total as we head to 15-30. A little bit of a worry.

A winner. Good timing for your first of the set.

But absolutely everything is coming off the middle of Wawrinka's strings at the moment.

A trademark backhand sets up break point...

Pat Cash
Former Wimbledon champion on BBC Radio's online-only commentary

Looking at the second-set stats, Stan is winning off the second serve which typically means he is winning the rallies. We saw Stan say to himself 'I need to be patient and show Murray I can win 30-shot rallies'. And he did.

Stan gets us under way at the start of this set as we tip beyond the two hour mark. This could be really lengthy if it goes the distance.

Very little change from the second set early on. 2015 champion Wawrinka hits a few ferocious forehands and comfortably holds.

Thanks JJ.

What's going to happen here? Murray needs to get back to the form of the opener that's for sure.

We won't have a winner at the end of this set of course but we'll have a good idea of which way the match is going to go.

Phew! This is utterly compelling - and utterly exhausting. Stan needs a quick comfort break, and so do I.

I'll leave you in the capable hands of Matthew Henry for set number three.

Three of how many on Chatrier today? It could be 10...

Pat Cash
Former Wimbledon champion on BBC Radio's online-only commentary

That was an interesting set.

Wawrinka was able to produce a few more winners and for Murray a few more errors crept in.

You have to take your hat off to Stan. He has to hit a lot of winners to win and that takes a lot of work.

And he takes it. With a belter of a winner, naturally.

Image source, Getty Images

Andy Murray still hasn't cracked down an ace today - has he now at 30-30? That would be timely. Nope, it's about half an inch wide of the centre line.

Stan Wawrinka pounces on his second serve, forcing Murray into an error. Set point Stan...

Hand over your serve here Andy and you're kissing goodbye to the second set...

Image source, Getty Images

First rule of breaking serve: hold your next service game by hook or by crook.

That's what Stan does after a game with some nervy moments for the Swiss.

A net volley into the tape hauls Murray level at 30-30, and another unforced error takes us into deuce...

He carefully watches a high ball onto his racquet, smashing down to safety so hard that he almost creates a pot-hole in the red stuff.

Murray overcooks a forehand in the next point, Stan clenches his fist as his parents applaud from his box.

Pat Cash
Former Wimbledon champion on BBC Radio's online-only commentary

It has been one of those matches, it has been nip and tuck.

That game highlighted how important it is to win the first point of game if you are the returner. It adds a bit of pressure.

Image source, AFP

You can't say it hasn't been coming. Murray loses focus, a double fault gifting three break points to Wawrinka.

The first one will do for the Swiss. Wawrinka has won eight of the past 10 points to take control of the second set.

Murray has taken to clapping his opponents a lot at Roland Garros. Is this something new? Not sure what the psychology in that is. But he looks like he is being sarcastic. I'd be getting riled if I was across the net. Maybe that's the tactic.

Anyway, it doesn't affect Wawrinka. A pretty straightforward hold for the Swiss third seed.

Image source, Reuters

Piers Newbery
BBC Sport at Roland Garros

We're used to monologues and pleading looks to the box during Murray's matches, but this time it's coming just as much from his opponent. Since losing a set he must feel he should have won, Wawrinka has been shrugging, pointing and chuntering in the direction of coach Magnus Norman, girlfriend Donna Vekic and the rest of Team Stan.

Pat Cash
Former Wimbledon champion on BBC Radio's online-only commentary

Image source, Reuters

Murray served his way out of that game. The most dominant shot in tennis is the serve and if you can get a few quick points on the clay it goes a long, long way.

Murray has got the cobwebs out. It has been very positive.

The positive attitude and body language doesn't always initially pay off but by the end it does. All of this shouting and screaming at your box can tire you out.

Almost nine minutes is the answer to that previous question.

Another yelp from Murray - this time it is "Let's go!" - as Wawrinka can't take the first break point of the second set.

Murray reacts similarly as he hits a forehand winner to nudge ahead, then seals a gutsy hold in the next point.

Phew. This is a rollercoaster of emotions. And we're only watching.