One half of the court is in bright sunshine and the other half in the shade as play gets under way for the day on Arthur Ashe Stadium.

Novak Djokovic, sporting a white cap to combat the sunlight, immediately brings up two break points in Zachary Svajda's opening service game.

The American saves them both, though, and goes on to hold serve.

Raducanu in full flow on Louis Armstrong and she carries on where she left in set one with a no-nonsense hold.

She looks great here but, of course, it's against the top opponents where questions remain around the Brit.

Jonathan Jurejko
BBC Sport senior tennis reporter at Flushing Meadows

Despite being lucky enough to have covered a fair few matches on Louis Armstrong Stadium, it never fails to make me laugh how much noise reverberates around the second show court.

There is a constant hubbub of chatter. It's like you're at a gig waiting for the band to arrive.

That clearly doesn't bother Raducanu. She is fully locked in and making light work of Tjen.

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Two brilliant shots painting the lines on one side of the court then the other leave Tjen scrambling and that's the set for Raducanu.

A very impressive set of tennis from Raducanu.

It's far from full on Arthur Ashe Stadium as Novak Djokovic enters the arena alongside Zachary Svajda.

Pretty sure plenty more spectators will drift in over the next few minutes.

The winner of this match could face Great Britain's Cameron Norrie in the third round - we'll be seeing Norrie in second-round action a little later today.

Just like that Raducanu brings up two set points.

She is absolutely dialled in.

Raducanu's impressive start continues as she takes the hold to love without issue in lightning speed.

The British number one is a game away from taking the first set. Qualifier Tjen will have to serve to stay in it.

Image source, Getty Images

Leon Smith
GB Davis Cup captain on BBC Radio 5 Sports Extra and BBC Sounds

Impressive hitting from Emma Raducanu. She has the ability to hit through her opponent and that's what she is doing.

It is the pace and consistent depth that Janice Tjen is struggling to cope with. She is getting rushed into the forehand and backhand, so she isn't getting time to land the slice she was utilising in the first round.

Jonathan Jurejko
BBC Sport senior tennis reporter at Flushing Meadows

Raducanu is looking to develop her serve as a weapon - and it has been very effective so far.

She has landed 71% of her first serves, winning 80% of them, which means she is quickly putting Tjen on the backfoot at the start of the points.

Lots of nods of approval from her team, led by new coach Francisco Roig.

It looks like a straightforward service game for Tjen but a double fault offers Raducanu a little glimmer.

The qualifier gets it done with a big serve that sends Raducanu one way before placing her forehand in her wake.

Jonathan Jurejko
BBC Sport senior tennis reporter at Flushing Meadows

If you watch Janice Tjen and think you've seen her before, then it might be down to her playing style resembling someone very familiar.

Tjen's topspin forehand, sliced backhands and willingness to come forward have been influenced by her hero Ashleigh Barty - the former world number one who retired in 2022.

But Raducanu is refusing to allow Tjen impose her game.

So far so good from the British number one, who is using her power from the baseline to force Tjen deep.

Leon Smith
GB Davis Cup captain on BBC Radio 5 Sports Extra and BBC Sounds

This is a really impressive start from Emma Raducanu.

We've already heard her being vocal so that shows she recognises how dangerous her opponent is. She is looking different, her body language is focused and upbeat.

She has got consistency in her coaching staff again now - and in Francisco Roig she has one of the most experienced coaches on the tour.

No signs of issue from Raducanu at this point and she takes another comfortable hold.

She looks locked in.

Image source, Getty Images

Novak Djokovic hopes the "physical struggle" he faced before powering to victory over American teenager Learner Tien in the US Open first round was simply down to a lack of match practice.

The 38-year-old Serb had not played since losing in the Wimbledon semi-finals in early July.

The 24-time major champion needed treatment for blisters on his toe after securing the second-set tie-break, but said the issue was not the reason behind his dip.

"I don't have any injury or anything. I just struggled a lot to stay in long exchanges and recover after points," said Djokovic. "I haven't played an official match in six weeks. I had to deliver my A-game, which I think I did in the first set.

"In the second, particularly, it was surviving on the court. In the important moments I just put one ball more in the court than he did."

Djokovic faces another American player - qualifier Zachary Svajda - in round two. Ranked 145th in the world, this is his fifth US Open and only the second time he has reached the second round.

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Alongside our updates on Emma Raducanu's progress, we'll also be keeping across the latest from Novak Djokovic's second-round match against home hope Zachary Svajda.

Djokovic won Grand Slam title number 24 at the US Open two years ago. That 25th Grand Slam singles crown, which would be a standalone record, has eluded the 38-year-old ever since.

He has played in just one of the seven Grand Slam finals that have taken place since that 2023 success, losing to Carlos Alcaraz at Wimbledon in 2024.

Some very dangerous serving out wide on display there from Tjen and she gets herself on the board with a hold to 30.

The qualifier is on the board.

Raducanu finds a first serve to save a third break point then a decent second serve to move to game point.

Another big serve shuts down any hope of Tjen cancelling out that break of serve and Raducanu extends her lead in set one.

Leon Smith
GB Davis Cup captain on BBC Radio 5 Sports Extra and BBC Sounds

Let's not underestimate how well Emma Raducanu is playing. She has the weapons, the tools and the movement to hit through the likes of Janice Tjen.

From a strategy perspective, Raducanu won't want to get into too many of those rallies where she is going backhand cross-court but not finding the width because that will allow Tjen to use her forehand from that backhand corner.

Image source, Getty Images

Raducanu saves both break points as Tjen goes wide then long for deuce.

But the qualifier has Raducanu on the defence and a punchy forehand brings up a third break back point.

Emma Raducanu's forehand is just looking a little loose in this service game.

A couple drop outside the lines and Janice Tjen takes advantage of a poor second serve to bring up two break back points.