Untidy again from Tomas Machac. With three errors in five points, he's staring a two-set deficit in the face.

Cam Norrie is certainly not lacking support out on court five.

There are huge cheers of encouragement as the Briton moves to 40-0 on serve with a forehand winner - but the pressure quickly returns after Luca Van Assche takes back a couple of points.

Well handled! Norrie pops away a closing forehand winner to stay in touch.

Toby Samuel has Tomas Machac on a string as he opens up the court for a backhand winner for 40-0.

For the first time in the match he finds himself in a bit of difficulty on serve, putting two backhands into the net and sending a wild forehand wide to present the Czech with deuce.

However, Machac can't capitalise, netting a low volley before firing a groundstroke long. That was perhaps his only opportunity to get back into this second set.

One thing you will always get with Cameron Norrie is a lot of fight, and the Briton is looking to bounce back immediately from losing serve as he forces his way to 0-30.

Luca Van Assche is still not giving much away cheaply, however.

The Frenchman hasn't been very vocal so far, but that's by far the biggest reaction he's given as he turns the game around at 40-30.

A short, sharp punch welcomes a hard-earned hold - and a 4-1 lead.

The crowd is trying to get behind Tomas Machac, cheering enthusiastically as he opens his service game with a backhand winner.

He follows it with a bruising cross-court forehand after dragging Toby Samuel out wide in the opposite direction and completes a hold to 15.

Simon Cambers
Tennis journalist at Flushing Meadows

Toby has had to work pretty hard.

A player who went to the States to play and his family, I think he has two older siblings, and his mum and dad backed those kids to try and do well and it didn’t work and Toby’s the one who’s showed the most talent and gone the furthest.

They have bankrolled his progress up to this stage and now he’s getting to the point where he might be able to start paying some of it back which will be great. They backed him to the hilt and I suppose you can only do what you want to do as a parent and they support Toby and his quest to become a professional tennis player and in the last 12 months, he’s really started making some strides and it’s been quite impressive watching him to be honest.

Alarm bells are ringing now for Cameron Norrie.

After missing two break points, the Briton now faces two following a series of misses.

Oh dear, oh dear. A double fault on the second gifts Luca Van Assche the advantage in set three.

Toby Samuel is yet to drop a point on serve in the second set.

Tomas Machac is still gesticulating and muttering in the direction of his team.

Image source, Getty Images

A much-needed hold for Tomas Machac.

It starts with a delicate, cushioned volley winner and ends with a venomous forehand.

It goes from bad to worse for Hugo Gaston as Daniil Medvedev breaks in the first game of the third set. The French player does eventually hold serve to stop Medvedev streaking to five straight games.

But it's a long, long way back for Gaston at this point.

Another terrific backhand winner takes Luca Van Assche to game point, but there's the latest cry of 'allez' from Cameron Norrie after watching his opponent miss the baseline.

Van Assche hits back with a one-two punch following a huge wide serve, and eventually gets over the line as Norrie nets.

That's a big game for the Frenchman - and his eighth in 11 since losing the third set.

Everything Toby Samuel touches is turning to gold.

Backhand winner behind Tomas Machac. Ace. Lofted forehand with the Czech stranded at the net. Ace. Lovely.

Tomas Machac stands with his hands on his hips after planting a forehand in the net.

Six games in a row for Toby Samuel, who is in cruise control.

Now then, can Cameron Norrie turn this into a serious opportunity?

The Briton gets to 0-30, and then two break points at 15-40 after Van Assche falters on a forehand.

Van Assche saves the second with a sublime backhand as he charges across his baseline for deuce.

Tomas Machac is unravelling. Two wild groundstrokes - both off his forehand - and he's shouting to his box.

He pulls one point back but then puts a down-the-line backhand into the tramlines. 15-40.

A faultless start to the second set for Toby Samuel, sealing yet another hold to love with a fizzing cross-court backhand.

Luca Van Assche isn't giving too much away, but he must be delighted with how well he is playing right now.

The Frenchman digs out a superb backhand winner from behind the baseline to take the opening point on Cam Norrie's serve - but the Briton digs in.

A couple of accurate forehands ensure that Norrie avoids an early setback.

Toby Samuel and Tomas Machac trade cross-court backhands before the Czech, somewhat inevitably, sends one long.

Samuel claims the first set in 23 minutes and without facing a challenge on serve - he only dropped two points across his four service games.

More difficulties for Tomas Machac on serve as he's pegged back to deuce from 40-0.

With a forehand winner, it's a set point for Toby Samuel.

The lengthy delay as we awaited Cameron Norrie's return to the court after the second set hasn't knocked Luca Van Assche off his stride.

An ace helps the 22-year-old along to a straightforward opening hold.