What a way to consolidate your break of serve as Alex Michelsen holds to love.

Frances Tiafoe must now serve to stay in the second set.

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Frances Tiafoe double-faults to put himself in a spot of bother before just coming up short in a monster rally which had the crowd on the edge of their seats.

Alex Michelsen played the finest of forehands at the end of that rally and it earned him a break point.

The world number 46 takes it as he comes into the net at just the right time to prevent Tiafoe being able to find the pass.

After being broken back in the last game, Michelsen responded brilliantly there.

Pam Shriver
Five-time Wimbledon doubles champion on BBC Radio 5 Live Sports Extra 2

Men come from two sets to love down all the time, but you get the sense that Frances Tiafoe has to win this set. The next 15-20 minutes is the most important part of the match for Tiafoe.

I want to see Tiafoe have a service game where his first serve looks free. He's playing handicapped at the moment because his first serve hasn't won him enough free points.

Can he find something in this quarter-final before it's too late?

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It's another break point for Frances Tiafoe but he just misses out with a forehand which drops the wrong side of the line.

Tiafoe gets another chance though, and the roars of encouragement from the crowd tell us they want him to take it.

I wonder if that gets into Alex Michelsen's head a little, as he then thumps a forehand into the net to gift Tiafoe the break a lot of the crowd wanted.

Pam Shriver
Five-time Wimbledon doubles champion on BBC Radio 5 Live Sports Extra 2

Tiafoe has lost some big matches here. Against Ben Shelton and lost an all-American semi-final to Taylor Fritz a few years ago.

I think the crowd will be right behind Tiafoe but he has to elevate his game and produce some of those charismatic points.

Frances Tiafoe is showing his frustration a little as he mistimes a forehand which loops wide.

He recovers well though as Alex Michelsen misses a couple of shots, before overcooking a volley at the net.

Tiafoe has break point but it's snuffed out with an ace.

Alex Michelsen sets the tone for the game with a smoking forehand winner down the line which Frances Tiafoe can do nothing about.

Tiafoe later goes wide to offer three break points, before closing both his eyes and looking to the sky in disappointment.

Tiafoe does well to save two, but can do nothing about the third as he is beaten by a backhand return winner down the line.

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Pam Shriver
Five-time Wimbledon doubles champion on BBC Radio 5 Live Sports Extra 2

These guys are trying to find their serve. If they're going to cause an upset in the semi-finals they need their serve to be a weapon.

It's also easy free points.

Alex Michelsen continues to look confident on serve and gets to 40-0 with Frances Tiafoe unable to get his teeth into the rallies.

A double fault lets Tiafoe back into the game, but Michelsen shuts him out as the 11th seed nets a forehand.

Frances Tiafoe has played some lovely volleys at the net today and brings out another to gain advantage, before sealing the hold as Alex Michelsen can't keep a big first serve in play.

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That's better from Francis Tiafoe as he forces Alex Michelsen into a mistake before a lovely forehand winner from just inside the baseline.

Alex Michelsen fights back though to make Tiafoe work for it, before forcing deuce as the latter drags a forehand wide.

That's the type of tennis Frances Tiafoe needs more of as a lovely slice prevents Alex Michelsen keeping the ball in play.

Michelsen recovers well with a couple of strong first serves before sealing the hold with a crushing forehand down the line.

That shot brought oohs from the crowd on Arthur Ashe Stadium, while Tiafoe is left with more thinking to do at the start of this second set.

Pam Shriver
Five-time Wimbledon doubles champion on BBC Radio 5 Live Sports Extra 2

For Michelsen to win his first set of his first US Open quarter-final, that was huge for him.

Frances Tiafoe gives a shake of the head in disappointment as he drags a forehand wide and the 11th seed finds himself in more trouble on serve at 0-30.

Tiafoe gets the better of a lengthy 17-shot rally, but Michelsen then brings up two set points by punishing a second serve.

Michelsen takes them this time before celebrating with a huge roar as Tiafoe can't control a forehand at the baseline.

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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.

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.

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Frances 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.

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.

Image source, Reuters

Alex 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.

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.