Watch: 'Do you think or not?!' Fuming Novak Djokovic gives umpire heated lecture during Wimbledon quarter-final

He may have earned his first Wimbledon semi-final spot in three years, but Novak Djokovic wasn't a happy camper during and following his quarter-final win over Kei Nishikori this morning.

Djokovic dispatched Nishikori in four sets with a 6-3, 3-6, 6-2, 6-2 win on centre court but he also felt he was locked in a battle with umpire Carlos Ramos who the Serbian accused of "double standards" in the contest.

The issues began in the third set when Djokovic was handed a code violation for unsportsmanlike conduct for bouncing his racket into the grass behind the baseline on tennis's most famous centre court.

Djokovic argued with Ramos he was going for a shot and happened to make contact with the ground but Ramos was having none of it.

"Do you think or not? Be honest," Djokovic asked.

Things got worse between the two later when Djokovic felt Ramos failed to sanction Nishikori for a similar act in the fourth set.

"Double standards, my friend. Double standards," he told the Portuguese umpire after the incident.

The semi-finalist went into more detail about his issues after the match.

"To be honest, I thought it was unnecessary to get a warning. I didn't harm the grass. I knew how I threw the racket," Djokovic later explained.

"It's not fair, but it's the way it is. In the midst of emotions in a tough match, it happens."

Djokovic faces Rafael Nadal in his semi-final on Saturday morning NZT.