Dominic Thiem looks to capitalise on Zverev's slight sign of injury with a deft drop shot, but undercooks it.

30-30.

And then double faults. Break back chance for the German.

Another Zverev backhands finds the net. And now the German is feeling his hamstring.

This doesn't look too good?

Thiem wrongfoots the German, but pops a flat forehand long.

He has Zverev scrambling again off the next point, and Zverev can only pump a backhand from inside the serve box into the tape.

15-15.

Leon Smith
GB Davis Cup captain on BBC Radio 5 live sports extra

Dominic Thiem is using the sliced backhand a lot which is a smart tactic on a heavy, moist court and to a tall player because the ball doesn't bounce much in these conditions.

Alexander Zverev drifts a sliced backhand harmlessly wide.

And Thiem breaks!

Double fault. Two break points. Early chance for Thiem in this set.

Zverev takes his frustration at losing that first set out with a thwack from height as Thiem drops a lofted ball just over the net.

He misjudges a swiveling backhand smash though, prodding it into the net as Thiem makes it 15-30.

Madison Keys is halfway to her first French Open semi-final appearance. She trailed 5-3 with opponent Yulia Putintseva serving for the set.

But the American 13th seed broke back in that 12th game and then took the tie-break 7-5 for the opening set.

Image source, AFP

How about that, right on the postage stamp of the T box as Dominic Thiem fires down an ace.

He quickly rattles his way to 40-0. And then game.

A quick hold for the Austrian.

Zverev serves and volleys, taking the point in the process. He's a big, big target to get around at the net.

The second seed holds.

Wayward from Dominic Thiem, complete with a groan that trails off into the grey Paris sky.

Just as ugly from Alexander Zverev on the next point, tugging it well wide.

15-15.

Leon Smith
GB Davis Cup captain on BBC Radio 5 live sports extra

Image source, AFP

Thiem was in control from midway in the set and he's starting to serve better and control more of the points.

Zverev's forehand does let him down sometimes and he hit too many loose shots. He will focus on getting more returns back in - he's only won 25% of points - and he needs to keep being offensive.

Well, Alexander Zverev has never beaten a top-10 player at a Grand Slam - despite winning four of his last five matches against top-10 opponents at Tour level - and he's going to have to come from a set down if he is to change that unwanted record today...

Mind you, he's already fought back from 2-1 down three times this tournament.

Dominic Thiem takes the next one. First set to the Austrian.

Just long!

Zverev somehow finds the energy to chase down every ball, but his loft shot from the net is met at close range by Thiem, who can only pop it long.

One set point to go.

Thiem lashes down a mammoth forehand that Zverev reaches, only to mishit and fumble it towards the net.

Two set points.

Wonderful from Dominic Thiem, a punchy serve complemented by a forehand winner.

Alexander Zverev hits back on the next point with a fist-pump worthy winner of his own.

30-15.

We are in a tie-break in the first set in the opening women's quarter-final between Yulia Putintseva and Madison Keys after the American wasted two set points in the 12th game. Will that come back to haunt her?

Image source, AFP

Leon Smith
GB Davis Cup captain on BBC Radio 5 live sports extra

Thiem looks the stronger physically but Zverev won't panic. He's come through some long matches this week and has come through a host of big matches this season so he will be feeling confident about turning this around.

Thiem drags a rare backhand wide, and Zverev holds.