Seventh seed Iga Swiatek has completed a comeback victory over France's Fiona Ferro.

After taking the second set in a tie-break, Swiatek claimed the third without conceding a game.

Game on? Not just yet. An ace for Zverev makes it 30-0 and a double fault at 40-0 is the only blip in a comfortable service game.

Can Ramos-Vinolas get himself up and running in this match?

Yes he can! An ace makes it a hold to love. Much better from the Spaniard after some first game nerves.

Zverev is serving confidently at the start of this match. The German cruises into a 40-0 lead but he sends a shot wide following a double fault...

No bother. Ramos-Vinolas can't capitalise and it's a first hold for Zverev to consolidate that break.

Ramos-Vinolas saves a second break point with a lovely forehand winner after a long rally, but Zverev makes the early breakthrough at the third time of asking.

The perfect start for the world number four.

Spaniard Albert Ramos-Vinolas gets us under way, but he's on the back-foot already after a couple of early errors.

Ouch. A double fault only makes things worse. Three break points for Zverev in the opening game.

Zverev beat American Sam Querrey in straight sets in his opener, while Ramos -Vinolas overcame Lucas Pouille in a tiring five-set encounter.

It was Germany's Alexander Zverev who ended world number one Novak Djokovic's hopes of a 'Golden Slam' - winning all four majors and the Olympic title - with victory in their Tokyo 2020 semi-final last month.

The 2020 finalist went on to win the gold medal and also triumphed in the Cincinnati Masters last week.

Next up on Arthur Ashe Stadium, men's fourth seed Alexander Zverev takes on Spain's Albert Ramos-Vinolas.

Stay with us for live text updates on that one, plus you can also listen to radio coverage at the top of the page.

Seventh seed Iga Swiatek is back in it against France's Fiona Ferro.

She was trailing by a set but despite losing serve twice, took the second in a tie-break.

The Pole is up a break already in the third.

What else is happening on day four at the US Open?

In the men's singles, Serbian world number one Novak Djokovic continues his pursuit of a calendar Grand Slam as he takes to Arthur Ashe Stadium to face Dutchman Tallon Griekspoor, after German fourth seed Alexander Zverev plays Spaniard Albert Ramos-Vinolas.

Sixth seed Matteo Berrettini and seventh seed Denis Shapovalov are up against Corentin Moutet and Roberto Carballes Baena respectively.

In the women's draw, tope seed Ashleigh Barty is already through, while Czech fourth seed Karolina Pliskova meets American Amanda Anisimova.

Sixth seed Bianca Andreescu faces Lauren Davis and 10th seed Petra Kvitova plays Kristyna Pliskova.

World number one Ashleigh Barty: "It was obviously really nice to be back out here. The crowd were incredible today.

"I try and keep my cards close to my chest. I've always been quite a calm person so that's an important part of my game but sometimes it's nice to let some of the aggression out.

"I used to practise my serve a lot when I was younger. I wanted to try and be accurate and use my serve effectively. But we do spend a lot of time practising."

World number one Ashleigh Barty is finally through. It took her three match points - the first at 5-3 - but she is into the third round of the US Open for a fourth time.

It's her 50th match win at a Grand Slam. It finishes 6-1 7-5 against Denmark's Clara Tauson.

American Shelby Rogers or Romanian Sorana Cirstea up next for Barty.

After her stunning run to the Wimbledon last 16 this year, just what can Emma Raducanu achieve in New York?

Oh. Ash Barty has broken back immediately. She will serve for the match again.

Emma Raducanu took just one hour and 21 minutes to knock out the world number 49.

Next up on her US Open debut will be world number 41 Sara Sorribes Tormo, following the Spaniard's 6-1 6-3 second round victory over Su-Wei Hsieh.

Oh wow! Wimbledon champion Ashleigh Barty had match point at 5-3 up in the second set but Danish teenager Clara Tauson held firm.

Barty then saved two break points as she tried to serve out the match but Tauson took her chance at the third time of asking.

We're now level at 5-5 in the second, with Barty a set up.

Someone's beating a drum in the background, which is really adding to the tension.

But there's no tension on the face of Emma Raducanu. Match point.

There's no getting to that. A booming backhand makes it 30-15 to Raducanu.

Two points to go for the 18-year-old.