US Open quarter-finals - listen to BBC Radio 5 Sports Extra commentary (UK only)
LIVE: Frances Tiafoe 5-7 3-6 7-5 6-3 Alex Michelsen in all-American tie
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 5-7 3-6 7-5 6-3 0-1 Michelsen
From two sets and a break down to drawing level. Frances Tiafoe is surely the favourite to win from here?
Alex Michelsen has other ideas though, as he kicks off the deciding set with a comfortable hold to love.
That will do his confidence a world of good.
Tiafoe 5-7 3-6 7-5 6-3 0-0 Michelsen*
Alex Michelsen decides to go for it but goes wide with a forehand.
Frances Tiafoe brings up two set points and takes them as Michelsen can't keep his backhand return in play.
We're going to a decider!
*Tiafoe 5-7 3-6 7-5 5-3 Michelsen
It's been a while since Alex Michelsen had a service game as comfortable as that, as he races to a hold to love in just 60 seconds.
Frances Tiafoe will now serve for the fourth set.
Tiafoe 5-7 3-6 7-5 5-2 Michelsen*
Alex Michelsen is having another word with himself as Francis Tiafoe gains advantage, before the 11th seed seals the hold with another strong first serve.
Tiafoe shouts towards his team in celebration.
Who can blame him, when he's one game away from levelling the match after being two sets down?
Image source, Getty Images*Tiafoe 5-7 3-6 7-5 4-2 Michelsen
Both players are struggling to hold it down on serve at the moment and Alex Michelsen is the latest to step up to earn two break points.
Frances Tiafoe is having none of it though as he takes the game to deuce with two big first serves.
*Tiafoe 5-7 3-6 7-5 4-2 Michelsen
Pam Shriver
Five-time Wimbledon doubles champion on BBC Radio 5 Live Sports Extra 2
Michelsen is showing emotions every time he misses a point and that will take a toll.
Image source, Getty Images*Tiafoe 5-7 3-6 7-5 4-2 Michelsen
Alex Michelsen saves the first break point but plants a forehand into the net on the second and Francis Tiafoe breaks to take control of the fourth set once again!
Tiafoe 5-7 3-6 7-5 3-2 Michelsen*
Is the momentum with Alex Michelsen now?
Frances Tiafoe might have something to say about that, as he triumphs in a rally with a lovely forehand winner which wrongfoots his American counterpart.
Michelsen nets the next point, before Tiafoe fires another forehand winner to bring up two break points.
Tiafoe 5-7 3-6 7-5 3-2 Michelsen*
What a response from Alex Michelsen!
This has turned into the engrossing quarter-final all the home fans hoped it would.
Frances Tiafoe just refuses to go away and shakes his fist after going from a fourth break point to a first game point after seven minutes.
He can't take his chance either, and Michelsen eventually ends his opponent's resistance to clinch a fifth break point. Game on!
*Tiafoe 5-7 3-6 7-5 3-1 Michelsen
Image source, ReutersAlex Michelsen is furious with himself - and takes it out on his team - after missing a third break point.
He's going to have a fourth chance, though!
A brilliant point from both players, but it's Michelsen who continues to hammer at the door as he slams down a final overhead.
*Tiafoe 5-7 3-6 7-5 3-1 Michelsen
If you were wondering whether Alex Michelsen could use that hold of serve to relaunch his bid for a place in the semi-finals, well he's giving it a good go!
The unseeded 22-year-old sets up two break back opportunities.
However, Frances Tiafoe scrambles back to deuce with a wonderful backhand winner. More huge moments in this match...
*Tiafoe 5-7 3-6 7-5 3-1 Michelsen
That is a much-needed hold of serve for Alex Michelsen.
After a run of seven games against him, the world number 46 gains a foothold in the set with a couple of aces helping him to safety.
Tiafoe 5-7 3-6 7-5 3-0 Michelsen*
A hold to love from Frances Tiafoe.
The crowd are absolutely delighted with this. It appeared for so long in this match that the 11th seed might go out with a whimper. Well, not any more!
Alex Michelsen is, clearly, not enjoying this so much. The 22-year-old has already made seven unforced errors in three games in this set. Having been so close to victory, this has become a mental battle as much as physical.
Image source, Getty Images*Tiafoe 5-7 3-6 7-5 2-0 Michelsen
Image source, Getty ImagesFrances Tiafoe roars with delight!
The American 11th seed has the breakthrough in the fourth set and appears to have all the momentum now.
A few errors from Alex Michelsen open the door - and Tiafoe does enough to take full advantage. It feels like the two players' performance levels are on very different trajectories right now...
Tiafoe 5-7 3-6 7-5 1-0 Michelsen*
After working so hard to keep his hopes alive here, Frances Tiafoe is immediately put under pressure in the fourth set as Alex Michelsen forces an early break point.
Tiafoe escapes, but a double fault prevents him getting over the line. He dusts himself down, wrong-footing Michelsen with a backhand, before his opponent sends a return long.
Relief for Tiafoe. Every single game feels crucial now.
Image source, Getty Images*Tiafoe 5-7 3-6 7-5 0-0 Michelsen
Frances Tiafoe has won four and lost five of the fifth sets he has contested at the US Open.
The 22-year-old Alex Michelsen has lost all five of the fifth sets he has contested on the ATP Tour.
The stats tell us we probably have to fancy the experienced Tiafoe if the 11th seed can take it that far.
His attempts to make a positive start to another must-win set are stalled as Michelsen reaches deuce in the opening game.
*Tiafoe 5-7 3-6 7-5 0-0 Michelsen
Image source, ReutersFrances Tiafoe brings up a second set point, and this time he takes it as Alex Michelsen mistimes a volley at the net.
Where has this come from? We're heading to a fourth set!
Tiafoe 5-7 3-6 6-5 Michelsen*
Frances Tiafoe plays the point of the match so far with a fine drop volley at the net which just spins out of reach from Alex Michelsen.
Michelsen is up against Tiafoe and the crowd at the moment, and after a brief fightback, he concedes set point by putting a forehand into the net.
This is pressure, but Michelsen rises to the occasion with a 133mph ace.
Tiafoe 5-7 3-6 6-5 Michelsen*
Francis Tiafoe is feeling it now as he serves only his second ace of the match, prompting another clenched fist in celebration from the 11th seed.
He then wraps up the game and Alex Michelsen must now serve to stay in the third set.
Image source, Getty Images*Tiafoe 5-7 3-6 5-5 Michelsen
Pam Shriver
Five-time Wimbledon doubles champion on BBC Radio 5 Live Sports Extra 2
What a signal Tiafoe has presented to Michelsen in this last couple of minutes!
