Controversy has erupted during the first Men’s Singles semi-final on Friday afternoon at Melbourne Park, with Alexander Zverev labelling the chair umpire’s decision to award Carlos Alcaraz extra time to recover from an injury as “f***ing bulls***”.

After winning the opening two sets 6-4, 7-6 (7-5), Alcaraz pulled up lamely on serve in the third, with the set tied at 4-4.

It saw the match briefly halted at 15-all, with the World No.1 clearly looking ginger in his upper right leg and groin region.

Chair umpire Marijana Veljovic quickly became the centre of attention for Zverev though, with the German extremely displeased with her decision to not start the countdown clock for Alcaraz on-serve.

“Why are you not starting the clock for 15 seconds?” Zverev rages.

“I have to see if he’s OK,” Veljovic replied.

Zverev added: “He’s cramping!”, before Veljovic finished by saying: “But I can’t know that.”

Alcaraz managed to somehow hold serve despite his clear niggle, forcing drop shots in an attempt to win the points as early as possible into the rally.

The Spaniard then called immediately for a medical timeout, and was seen receiving physio treatment — as well as drinking pickle juice — while Zverev continued to air his grievances with the chair umpire for the extra time his opponent was given to recover.

“This is f***ing bulls***,” Zverev raged.

Players are not able to call for a ‘Medical Time Out’ if suffering with cramp, explaining Zverev’s outburst. Pickle juice is commonly consumed by athletes to help combat cramp.

Former American tennis player Jim Courier sympathised with the German on-air for Nine, agreeing a clear mistake had been made.

“This is such a travesty. They have totally botched this. That’s why Zverev is melting down right now,” Courier said.

Zverev went on to win the third set in a tiebreaker 7-6 (7-3), as doubts over Alcaraz’ fitness continued to grow. It is the first set the World No.1 has dropped all tournament.