Jakub Mensik flailed his arms and threw his towel in anger after drug testers tried to make him do a test midway through his Next Gen ATP Finals match with Arthur Fils.

The tension was high in Jeddah, with Mensik in desperate need of a victory after losing his first match against Learner Tien. He was a set down against Frenchman Fils when he requested a toilet break.

However, upon returning to the court, a baffled Mensik told umpire Nacho Forcadell that he was cornered and asked to conduct an anti-doping test. Exactly what was said between Mensik and the umpire is not clear, but Forcadell was heard saying: "You're right."

The Spanish official then radioed a colleague, saying: "Someone from anti-doping in the middle of the toilet break wanted to test him now, and that delayed everything. So if you could talk to them - that should not happen."

The match finally resumed following the delay, with Fils going on to claim a straight-sets victory, prevailing 4-2 4-3 4-2.

Mensik, a 19-year-old Czech up-and-comer currently ranked 48th in the world, will be up against it when he faces Joao Fonseca in his final group game on Friday. An early exit would be a crushing blow for Mensik, who admitted he came to Saudi Arabia with an overall win in his sights.

"It was one of my biggest goals to reach this event before the season," he told the ATP Tour leading up to the tournament. "I'm glad to be here. So far it's amazing, the facilities and everything that they did for us.

"You can feel really that you're one of the best younger players in the world. I never have expectations. Obviously just to enjoy this beautiful tournament [is my goal]. Of course I would be happy to win a couple of matches and of course I'm going here to win it."

Standing 6ft 3in tall with a slim build, Mensik compares himself to current world No. 1 Jannik Sinner and would love to replicate the Italian's 2019 Next Gen win. "I like Sinner," he said. "A tall player like me and he is still moving so well.

"It is similar to me in my opinion because I’m already tall and I can move well on the court. With the forehand, I have a similar technique and style to Jannik. I can’t be like Carlos Alcaraz because he’s smaller and stronger. I’m the guy who is skinnier. When you see a lot of tall guys now, they have a big serve and big weapons. My serve is also a very big weapon."