John McEnroe
Three-time Wimbledon singles champion on BBC TV

Taylor Fritz is number one in the ace department [with 49 aces], it doesn't look like in a way that his serve is that huge because of who he's playing, but Fritz has got one of the biggest first serves in the game.

No 10-minute marathon this time!

Gabriel Diallo holds to love with a second serve into the body that Taylor Fritz can only try to fend off, trying to get it back over the net just wasn't an option.

Serious heat on that second serve.

The contrast between Gabriel Diallo's service games and Taylor Fritz's is stark.

Fritz rushes through another of his in next to no time, holding to love.

Diallo will be hoping for something similar as he aims to retain his break advantage and force a fifth set.

John McEnroe
Three-time Wimbledon singles champion on BBC TV

Gabriel Diallo is proving to be quite resilient himself, an impressive quality if you want to make it big in the tennis world.

Twice Gabriel Diallo has been really challenged by Taylor Fritz on his serve and twice the Canadian has passed the test.

Another service game that comfortably exceeds 10 minutes but Diallo holds firm, saves break points and does enough to hold.

He remains a break up.

Chris Bradnam
BBC Sport commentator at Wimbledon

It's another big test from Gabriel Diallo here, he's giving nothing to Taylor Fritz.

Back under way and Gabriel Diallo saves the second of those two break points as Taylor Fritz's forehand drops wide.

It's threatening to turn into another very lengthy service game for Diallo, though, as Fritz then saves two game points - the second when the Canadian tamely puts a volley into the net.

Taylor Fritz is pushing and brings up two break points.

He's scrambling throughout the first of them, just barely getting to the ball on numerous occasions during a brilliant point.

The American dives to reach the ball after a drop volley from Gabriel Diallo, an incredible get but the Canadian has an open court and calmly puts away the volley at the end.

Fritz cut himself on the elbow with that dive so he's taking a medical timeout - and will have another break point when play resumes.

After that mammoth service game for Gabriel Diallo, Taylor Fritz breezes through his next one.

The American fifth seed holds to 15 but remains a break down.

John McEnroe
Three-time Wimbledon singles champion on BBC TV

There have been numerous games that have been over in under a minute, this is the equivalent to at least six games right now for these guys or more.

After an epic game, Gabriel Diallo holds!

He staves off another break point as Taylor Fritz goes long before a fabulous forehand gives him advantage again.

Fritz takes it back to deuce but a 142mph ace gives Diallo another chance - and, finally, he takes it...

With a second serve ace, what else?

Chris Bradnam
BBC Sport commentator at Wimbledon

The quality of tennis right now is just fabulous, this is a big big game!

Nice work at the net from Taylor Fritz earns him a break point.

But Gabriel Diallo does as he has done since the restart and goes on the attack.

He comes forward and whips a forehand out of reach of Fritz before bringing up another game point with an ace.

Fritz denies him again. Deuce again.

John McEnroe
Three-time Wimbledon singles champion on BBC TV

Image source, Getty Images

One thing you can be rest assured about is that Taylor Fritz will keep battling point in and point out, he's one of the best competitors out there.

Gabriel Diallo raced into a 40-15 lead as he tries to consolidate the break but Taylor Fritz grinds it out to get to deuce.

Twice Diallo gets to advantage but each time Fritz responds, the second time by getting after a kick serve out wide with a passing winner down the line.

Deuce.

John McEnroe
Three-time Wimbledon singles champion on BBC TV

It looks like Gabriel Diallo got some good advice. A lot of this took place because Taylor Fritz simply didn't hit his spots there and allowed Diallo to unload on some forehands.

Big early break for Gabriel Diallo!

He is letting loose, playing his shots and trying to get after Taylor Fritz.

After smoking a backhand down the line to bring up break point, he skews a forehand wide after Fritz's second serve lands just on the line.

But Diallo earns another break point and takes this one as his American opponent slips on the baseline.

Gabriel Diallo rips a forehand winner down the line on his way to a comfortable hold.

Good, positive start to the fourth set from the Canadian.

Chris Bradnam
BBC Sport commentator at Wimbledon

It's a very comfortable game for Taylor Fritz, just nine points conceded on serve since the start of the second set.

Back under way on Court One and after bigging up Taylor Fritz with that unforced error stat, he produces one from the first point back with a forehand that drifts long.

No bother for the American, though. He goes on to hold to 15.