US Open quarter-finals - listen to BBC Radio 5 Sports Extra commentary (UK only)
LIVE: 11th seed Frances Tiafoe faces fellow American Alex Michelsen
Tiafoe bidding to reach third US Open semi-final, Michelsen has never been this far in Grand Slam
Two-time defending champion Aryna Sabalenka beats Linda Noskova 7-6 (7-1) 3-6 7-6 (10-7) to reach semi-finals
Sabalenka will lose world number one ranking if Elena Rybakina reaches last four
*Tiafoe 5-6 Michelsen
Alex Michelsen has hit 15 winners to Frances Tiafoe's four so far.
The American world number 46 comes through another confident service game to love with Frances Tiafoe unable to get a foothold in the game.
Tiafoe 5-5 Michelsen*
Pam Shriver
Five-time Wimbledon doubles champion on BBC Radio 5 Live Sports Extra 2
What a mature set-point. Tiafoe made sure when he stepped up to the line he was 100% committed to the target.
Michelsen will be a little disappointed.
Image source, Getty ImagesTiafoe 5-5 Michelsen*
Image source, ReutersFrances Tiafoe comes through deuce to hold as he gets the better of a short rally with Alex Michelsen.
The American 11th seed dealt with that bit of pressure well there.
*Tiafoe 4-5 Michelsen
Alex Michelsen looks a bit annoyed at himself as he puts a forehand into the net, but a double fault from Frances Tiafoe brings the score to 30-30.
There's a bit of pressure on the 11th seed now, and it shows as he misses a volley on the stretch at the net to offer set point to Michelsen.
It's well saved though, as Tiafoe slams a big first serve down the middle which Michelsen can't keep in play.
*Tiafoe 4-5 Michelsen
Image source, ReutersAlex Michelsen has settled into his serve now as he wraps up another quick service game.
He clenches his fist in celebration and walks over to his chair before the change of ends.
Frances Tiafoe is about to serve to stay in the set.
Tiafoe 4-4 Michelsen*
Frances Tiafoe doesn't give Alex Michelsen much room to play with as he serves into his body to edge ahead in the game.
Tiafoe gets the better of a couple of short rallies to hold as Michelsen plants a backhand into the net.
There's not much between these two right now.
*Tiafoe 3-4 Michelsen
That's the most confident service game of the match so far as Alex Michelsen wraps up a hold to 15 with a booming ace down the middle.
Can he now put the pressure on Frances Tiafoe's serve again?
Tiafoe 3-3 Michelsen*
Alex Michelsen gives a shake of the head in disappointment as he drags a backhand wide when well-positioned.
He recovers well though to earn break point as Frances Tiafoe continues to struggle on serve, but can't take it as he plants a forehand into the net.
After gaining advantage, Tiafoe secures his first hold of the match with an ace.
Image source, Getty Images*Tiafoe 2-3 Michelsen
Alex Michelsen gets the better of a rally and Frances Tiafoe wears a thoughtful expression as he takes a breather at the back of the court to dry off with a towel.
The breather seems to give Tiafoe a reset, as he fights back to earn break point with a lovely drop shot at the net.
The pair go at it again in a rally, before Tiafoe brings out another drop shot to secure the break.
I make that four breaks of serve in the opening five games.
Tiafoe 1-3 Michelsen*
Pam Shriver
Five-time Wimbledon doubles champion on BBC Radio 5 Live Sports Extra 2
I think you want to test that side more and more, you get used to going one side.
Michelsen looks devastating at the moment.
Tiafoe 1-3 Michelsen*
Frances Tiafoe has beaten Alex Michelsen in both of their previous two encounters but there are signs he's going to face a tougher challenge today.
Michelsen gets to 15-30 before earning two break points as Tiafoe can't control a volley at the net.
Michelsen lets one slip away, but makes the second one count as Tiafoe spoons a forehand long.
Image source, Getty Images*Tiafoe 1-2 Michelsen
That's better on serve from Alex Michelsen as Francis Tiafoe is unable to get the ball back into play.
Michelsen secures the hold with after a lovely forehand winner across court and gives a little fist pump in celebration before the change of ends.
Tiafoe 1-1 Michelsen*
Both players have yet to settle into their serve yet as Alex Michelsen earns three break points of his own.
Frances Tiafoe gives a puzzled look towards the court after the ball appeared to clip the baseline, before being beaten by a superb backhand down the line.
We're back level again.
*Tiafoe 1-0 Michelsen
Arthur Ashe Stadium is still half-empty as fans take a breather after that epic Aryna Sabalenka win earlier.
The fans who are yet to return have missed a confident start from Frances Tiafoe, who earns two break points and makes them count as Alex Michelsen goes into the net.
Tiafoe v Michelsen
Image source, Getty ImagesFrances Tiafoe's match against Alex Michelsen means at least one American man will be guaranteed to reach the US Open semi-finals.
If Ben Shelton beats two-time champion Carlos Alcaraz in the evening session, he could make it two.
Tiafoe has reached the last four at Flushing Meadows twice before, but has never got to a Grand Slam final.
Michelsen, meanwhile, is playing in his first Grand Slam quarter-final and is happy to have gone under the radar so far in New York.
"First, second, third rounds, all matches I'm feeling nerves. It's a human experience," he said.
"But it's just about going out there and managing them to the best of my ability. I feel like I've done that very well."
Lapthorne/Els 7-6 (7-5) 6-1 Wagner/Bogdanon
Great Britain's Andy Lapthorne is through in the men's quad wheelchair doubles alongside South African partner Leon Els.
They beat American pair David Wagner and Andrew Bogdanov 7-6 (7-5) 6-1 to reach the semi-finals.
Fellow Briton Greg Slade is currently a set down alongside Australian partner Heath Davidson to Dutchman Niels Vink and Israel's Guy Sasson, however.
Later today, Britons Alfie Hewett and Gordon Reid play France's Stephane Houdet and China's Ji Zhengqing as they also attempt to reach the last-four.
Tiafoe v Michelsen
Image source, Getty ImagesWhat a match that was to kick things off on Arthur Ashe Stadium today.
Next up though, is the all-American quarter-final between 11th seed Frances Tiafoe and world number 46 Alex Michelsen.
Tiafoe reached the last eight with a straight-set victory over Russian seventh seed Daniil Medvedev, while Michelsen is yet to drop a set this year at Flushing Meadows.
The pair have met twice before, with Tiafoe winning on both occasions.
Sabalenka 7-6 (7-1) 3-6 7-6 (10-7) Noskova
Sabalenka speaking after the match: "What a battle, what an incredible player she is. I'm speechless right now because I was pushing myself to the limit in this match especially the third set. I honestly thought that's it, the match is over.
"Super happy to get this win, thank you guys for being amazing. Thank you for the support."
On not losing a tie-break at the US Open: "This has boosted my energy and confidence. I'm super glad I made that Ace it's a very important point. It just shows that I'm ready to fight and I'm happy to see that."
On what she will work on for the semi-finals: "A better game than that, I think I approached the net a couple times. I will work a bit extra on that part of my game. For now I just want to relax and recover and reflect what has just happened."
Sabalenka 7-6 (7-1) 3-6 7-6 (10-7) Noskova
Aryna Sabalenka will play the winner of the all-American tie between third seed Jessica Pegula and 26th seed Emma Navarro in the semi-finals.
That match is later today on Arthur Ashe Stadium just after 00:00 BST.
Sabalenka 7-6 (7-1) 3-6 6-6 (7-6) Noskova
Annabel Croft
Former British number one on BBC Radio 5 Sports Extra 2
It was a brilliant match.
That's going to be a painful defeat for Noskova. She looks very dejected.
You have to admire the spirit of Sabalenka. Something has shifted in her. What a match. It was fantastic.
Image source, Getty Images
