This will also go someway to keeping Medvedev zen-like (relatively). Another hold keeps him on track in the second set.

I wouldn't say Medvedev is calm. Certainly calmer. Some dark, deep thoughts appear to be wandering through the Russian's mind as he sits on the chair.

Thiem exhales heavily as Medvedev bats a return into the net for 40-15. I'm out of breath just watching.

That Thiem single backhand - which should be designated as a thing of natural beauty - gets the Austrian on board in the second set.

Now the Russian needs solid hold. Three first serves help him into a 40-0 lead, Thiem's wayward forehand clinching his first hold-to-love.

More like it Daniil son.

Feel sorry for the ball. Medvedev is taking his anger out on that. It works though.

His heavy-hitting forces Thiem into a couple of mistakes and the Austrian then coughs up a double fault.

Break points Medvedev... another mistake from Thiem hands it over on a plate.

Well, well, well.

Medvedev was the pantomime villain on Ashe last year, you will remember. Reckon they'd have been booing him Ivan Drago-style if they were in the house.

Medvedev goes off to the bathroom. Presumably to slam the door repeatedly rather go for pee.

Well... that escalated.

Thiem keeps his cool while Medvedev loses his, winning 10 of 12 points to stroll to the first set.

Talking of rattled... that's Medvedev. The Russian is still chuntering at the changeover.

Meltdown from Medvedev.

Thiem just waits patiently at the other end.

Then when the match resumes he rattles through the hold.

The second? Uh oh... it's gone! After a poor line call. Medvedev is FURIOUS!

He isn't allowed to challenge the call and tells the umpire exactly what he thinks.

"Is the US Open a joke?"

Here we go! Medvedev can combust and the fuse has been lit. He goes around the net to point at the mark - he's not allowed to do that.

A US Open official tells him exactly that.

"I think I killed someone. My sincere apologies for crossing the net. It is OK. Sorry. Sorry."

He isn't being sincere.

Medvedev has only faced nine break points in the whole tournament going into this match.

Here are another two already tonight. The first one saved...

Cheers Saj. Not banking on it.

Five... all the way. And a marathon breaker.

So I hand you over to Jonathan Jurejko.

All over in three?

Thiem races through his own service game to love.

This is impressive from the three-time Grand Slam finalist.

Break point Thiem with a great backhand down the line.

Only the 10th break point the Russian has faced.

It's saved thanks to the Austrian's backhand error.

Medvedev eventually holds. Another toughie on his serve.

The Austrian second seed is really troubling Medvedev with these sliced backhands.

0-30.

These players are playing twice as fast as the previous two. Thiem picks up brilliantly from the corner and forces the error to bring up game point.

The Austrian serves his first ace to hold once more.

Deuce.

A sliced backhand error from the baseline annoys Thiem - he lets out a cry.

The Russian seals as he dances to the net and dispatches a winning forehand.

The Austrian looks very good though in these early stages.

What a sliced drop at the net from Thiem.

I've also noticed that both players barely have any backlift on their strokes but generate so much power.

15-15.