The final afternoon match at Arthur Ashe stadium involves another of the USA's hopes. No.20 seed Coco Vandeweghe locks horns with Lucie Safarova from the Czech Republic. The winner will meet world No.1, Karolina Pliskova in the last eight.

GAME, SET AND MATCH! - VANDEWEGHE 6-4 7-6 SAFAROVA. Coco books her place in the last eight for the first time with a hard-fought, mature victory over Safarova. The American finished the tie break with an ace to take it 7-2 and conclude a real battle in one hour and 39 minutes. She will now meet world No.1 Karolina Pliskova.

TIE BREAK UPDATE: Coco leads 4-2 at the change of ends.

VANDEWEGHE 6-4 6-6 SAFAROVA. The time break cometh. No nerves from Safarova as she produces a delightful pass to clinch a love hold and take it into the breaker.

VANDEWEGHE 6-4 6-5 SAFAROVA. Consistent, powerhouse hitting from Coco as she confidently holds to 15. She'll at least play a tie break, but can win it in the next game if Safarova's serve falters.

VANDEWEGHE 6-4 5-5 SAFAROVA. Lucie survives a scare to stay alive. A third double fault gives Coco a glimmer at 15-30, but she misses a return by millimetres and from there Safarova steps it up. All square. Any error now from either player and it'll cost them the set/match.

VANDEWEGHE 6-4 5-4 SAFAROVA. Coco gratefully takes another Safarova miss in her stride, finishing off a love hold with a wide ace. She's one away from the last eight.

VANDEWEGHE 6-4 4-4 SAFAROVA. Lucie with a real contender for miss of the tournament. She strolls forward to put-away a simple overhead and somehow dumps it into the net from less than a yard. It seemed harder to do that than get it into the open court. Luckily for her, it's at 30-0 and doesn't affect the outcome of the game as she re-focuses to level it up.

VANDEWEGHE 6-4 4-3 SAFAROVA. It's been a really gritty display from Coco. She comes under fire once again, but despite being scolded by a return winner to peg her back to deuce, she finds some hefty serves to grab the scoreboard advantage at a significant moment in Set 2.

BREAK! - VANDEWEGHE 6-4 3-3 SAFAROVA. Superb reply from Coco. She berates herself for letting a 0-30 lead slip but then hits a lovely return to earn the break back opportunity. A rifled backhand to Safarova's right flank is too hot to handle and the Czech fires wide to allow the American to level.

BREAK! - VANDEWEGHE 6-4 2-3 SAFAROVA. Finally Lucie gets her break. Vandeweghe fends off the first of double break point with a blistering serve, but then hooks wide into the tramlines on the second. We could well be going to a decider here.

VANDEWEGHE 6-4 2-2 SAFAROVA. A 13th winner puts Lucie well in control at 40-0 but she lets it slip to deuce. It's a mixed service game including two double faults, but she finds a big first serve to save a BP and eventually scraps her way through.

VANDEWEGHE 6-4 2-1 SAFAROVA. What a miss. Safarova wastes another big chance to crank up the heat and make deuce, racing into the net and firing wide of the tramlines as Coco guessed the other way. The crowd are mainly behind the American but even they are beginning to feel surprised that Lucie continues to let her off the hook.

VANDEWEGHE 6-4 1-1 SAFAROVA. The Czech world No.37 will be hugely frustrated but her expression remains unchanged. She maintains composure and cruises to a love hold to get on the board.

VANDEWEGHE 6-4 1-0 SAFAROVA. Deja vu as Safarova starts like a house on fire, but gets no reward. She works her way into a 15-30 lead, but Coco has been nothing if not resilient so far and digs out another hold from a tricky position.

SET! - VANDEWEGHE 6-4 SAFAROVA. Lucie pays the price - bigtime! Coco hits freely after her great escape and snares triple set point. The American hammers an un-returnable forehand on the second of them to clinch a tight opener in 43 minutes. She clenches her fist and looks to the stand where a pensive Pat Cash joins in with the crowd's applause and gives her a nod of approval.

VANDEWEGHE 5-4 SAFAROVA. Third time - but still unlucky for the Czech. She has had break point in three separate games but just can't find the shot to make it count. Vandeweghe clings on and produces some brave, powerhouse hitting in some tense rallies to stay afloat. The pressure switches to Safarova now who must hold to stay in the set, with those missed opportunities still lingering in her mind...

VANDEWEGHE 4-4 SAFAROVA. The American No.20 seed loses it. She argues with the umpire, mutters expletives to herself and then throws her racket to the floor as she loses a poor return game. This should be music to Safarova's ears, particularly at this juncture in the set.

VANDEWEGHE 4-3 SAFAROVA. Coco has had a couple of tough holds, but finds better rhythm and lands the first serve to help her claim a less arduous hold this time. She drops just one point and stays in the box seat heading into the business end of Set 1.

VANDEWEGHE 3-3 SAFAROVA. Best service game so far from Safarova. She breezes to a love hold and the pressure returns to Coco's shoulders all too quickly from her perspective.

VANDEWEGHE 3-2 SAFAROVA. 'Come on!' cries Coco as she snares the advantage from deuce. Once again she's made to swat away a break point, but produces a very smart, angled second serve catch Safarova out and keep her nose in front.