This has proved to be Fritz’s breakthrough moment in his 33rd Grand Slam appearance.

He lost to Novak Djokovic in the US Open quarter-finals in 2023, twice lost in the last eight at Wimbledon in 2022 and July this year and suffered defeat in the Australian Open quarters in January.

After sharing two tight sets, the crucial moment came deep in the third when Zverev looked to have the momentum, having recovered an early break.

He missed a straightforward backhand on break point at 4-4 which allowed Fritz to hold and then the fourth seed offered up three forehand errors to fall 0-40 behind.

Zverev held off those three set points but Fritz eventually broke through at the fifth attempt.

Fritz, who also beat Zverev from two sets down at Wimbledon this year, was able to neutralise the German’s booming first serve and remain the more solid with the finish line in sight while hitting powerful serves of his own.

He gained the initiative in the fourth-set tie-break by taking the first point on the Zverev serve and won a gruelling 24-point rally for the second break and a 5-2 lead.

Fritz faltered momentarily, pushing a nervous forehand wide, but Zverev offered up two more errors to seal the result.

Zverev said afterwards it was the most angry and disappointed he had felt after a match in a “long time”.

“I played terrible,” said Zverev, who was unusually flat in the final set and complained about his racquet throughout as he chased a first Grand Slam title and a third US Open semi-final.

“I just have no answers right now. He played quite a good match. I did nothing to deserve to win.”

On the prospect of an all-American semi-final against Tiafoe, Fritz said: “I know the crowd would really want to see me play Frances so we get an American in the final.

“That could be crazy, so I guess we’ll see what happens – but either way I’ll be ready to go.”

Britain’s Jack Draper is among those remaining in the top half of the draw. He plays Alex de Minaur in the quarter-final on Wednesday.