Botic van de Zandschulp, who stunned world number three Carlos Alcaraz at the US Open on Thursday, was contemplating retirement less than three months ago.

Tired of playing through pain from a nagging injury, and demoralized by early defeats after his ranking fell and he found himself unseeded at tournaments, he opted to play a couple of lower level Challenger events to build his confidence back up.

“The tour is tough,” van de Zandschulp, ranked 74th, said. “You can play well but you can (still) only play two matches a week if you play well. If you’re not seeded in a tournament you can face (Jannik) Sinner first round.

“You can play well but still in the end you will lose a lot of matches.

“I needed more confidence after Wimbledon. I played a couple of Challengers in Europe. I think that gave my confidence a boost.”

Van de Zandschulp said it wasn’t a difficult decision to play the Challengers.

“I think I already had the tough part behind me, dropping from 25 to 70, not being seeded. I was just happy to play more matches, to win more matches.”

He seized control early against Alcaraz, but admitted he was waiting throughout the match for the Spanish star to raise his game.

“You think he’s one of the best players in the world, he’s going to come up with a next level,” van de Zandschulp said.

“Even in the third you’re thinking he’s going to come up with something special, and I broke him again pretty quick.”

Knowing Alcaraz’s aggressive style, van de Zandschulp said he tried to “beat him to the punch”.

“I tried to come into the net so he wasn’t able to,” said the Dutch player, who was still getting to grips with his achievement an hour after the match ended.

“I’m still processing it,” he said. “Maybe in a couple of hours or tomorrow I’ll feel a little bit more emotional with what happened tonight.”