We're going to park our live text here but coverage continues on 5 Live, which you can listen to via this page.

Among the players currently in action are men's ninth seed Taylor Fritz, who is in the first set against Mattia Bellucci, and women's 10th seed Amanda Anisimova, who is into a deciding set against Lilli Tagger.

Later today, Fran Jones, who is the last remaining Briton in the singles draws at the US Open, takes on American 14th seed Iva Jovic.

We'll be back to cover that match, which is fourth on Stadium 17.

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Some comeback from Madison Keys to beat Anna Bondar and progress.

The 2017 runner up was 5-2 down in the deciding set and seemingly on her way out but she fought back to take the game to a tiebreak, which she came out on top of to reach the third round.

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Naomi Osaka, speaking at Arthur Ashe stadium after victory: "The match was definitely really tough, and I just felt like I was a little bit too hard on myself after opportunities in the second set.

"I took the bathroom break, regrouped a little, came back and just tried to have no regrets.

"I just told myself that it's an honour to play on this court, honestly.

"I just want to keep playing in front of you guys if possible, so to keep fighting as best as I can.

"The energy from the crowd, it's very lively and I have the experience of growing up here and playing on this court many times. It's really fun."

Katie Smith
Presenter on BBC Radio 5 Sports Extra 2

There is now one British player left in the US Open - Francesca Jones.

Jones is in action later today as she faces Iva Jovic in the second round.

Harriet Dart just can't land a first serve at the moment and Marie Bouzkova punishes the Briton with a forehand return winner to take the game to deuce.

Dart shows composure to secure the hold, but she now must break Bouzkova to stay in the match.

Marie Bouzkova continues to look comfortable on serve and she secures a relatively simple hold as Harriet Dart puts a backhand into the net.

The Czech 25th seed is one game away from the third round.

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Harriet Dart continues to struggle for consistency as Marie Bouzkova punishes a couple of second serves as the game heads to deuce.

Dart swings her racquet dejectedly after a wayward forehand gives break point to Bouzkova, but she makes up for it next point with a superb forehand winner.

Dart eventually comes through to hold by getting the better of a couple of rallies, before she's congratulated by some warm applause from the crowd.

Marie Bouzkova races through her service game to hold to love.

The Czech 25th seed has now won seven games in a row.

Naomi Osaka is moved across the baseline by Katerina Siniakova and eventually sends a forehand wide for 15-30.

The former world number one finds an angle to force Siniakova into the net for 30-30 and shakes her fist in delight after a miss from the Czech brings up match point.

Katie Smith
Presenter on BBC Radio 5 Sports Extra 2

This one is starting to run away for the British qualifier.

Naomi Osaka will believe that should be that.

The former champion rises to a key moment and swats away another winner to secure the double break and the chance to serve this out for the second time.

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It's all coming undone for Harriet Dart as she serves another double fault to gift Marie Bouzkova three break points.

Dart fights back to save the first two but she can't rescue the third as she slams a forehand into the net.

It's a long way back from here for the Briton.

Naomi Osaka is frustrated at her failure to put pressure on Katerina Siniakova as she falls 40-15 down on the Czech's serve.

A couple of misses from Siniakova keep the 13th seed interested, however.

A mis-hit from Osaka allows Siniakova another chance to escape - but Osaka volleys in, before repeating that tactic to reach break point.

Marie Bouzkova has all the momentum right now as she consolidates her break with a relatively trouble-free game.

The Czech 25th seed wrapped it up with a magnificent forehand winner down the line from the baseline.

The crowd enjoyed that one.

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Naomi Osaka saves the first break point with an ace, before making her way back to deuce as Katerina Siniakova misses a backhand.

Another ace - Osaka's 10th of the match - gives the former world number one game point, and she escapes from a really tricky situation to edge closer to victory.

Was that Siniakova's big chance? The past hour suggests we shouldn't try to predict anything.

Pat Cash
Former Wimbledon champion on BBC Radio 5 Sports Extra 2

Once Marie Bouzkova gets on a roll, she can motor through.

With her other Czech players doing well, she will think it is her turn now.

She is so consistent.

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Harriet Dart is struggling with the ball in her hand as she serves her fifth double fault of the match.

Marie Bouzkova then controls a rally from the back of the court, forcing Dart into an error, to earn break point.

Dart can't save it as she slices a forehand tamely into the net.

Just the start to the second set the Briton would have been hoping to avoid.

We could have another twist!

That's long from Naomi Osaka - and that will be two break back points for Katerina Siniakova.