Daniil Medvedev totally lost the plot with a belligerent rant at the umpire over what he felt was constant coaching from Stefanos Tsitsipas's father during their Australian Open semi-final.
The No. 2 seed, known for his fiery temper and penchant for a mid-match scream at the umpire, shouted in abusive fashion at the official over because he felt his opponent should have received a coaching violation.
Tsitsipas has often had opponents accusing him of receiving advise from his father, who loves to be as involved as possible from the stands during his son's matches at major tournaments.
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Medvedev could not contain his emotions after having his serve broken to trail 5-4 in the second set after having won the opener, and let out his frustration at the umpire with Tsitsipas and his father also in the crosshairs.
"Are you stupid?" a furious Medvedev yelled at the umpire at the changeover.
"Are you mad? Are you mad? And his father can talk every point? Wrong!
"His father can talk every point? His father can talk every point! His father can talk every point?! Answer my question!
"Will you answer my question? Can you answer my question please? Can his father talk every point?
"Oh my god! Oh my god! You are so bad, man! My god, how can you be so bad in a semi-final of a Grand Slam? Look at me! I am talking to you!
"Give him a coaching [violation] - because he is talking every point. What time? I am talking."
Moments later, Medvedev dished out a pretty unusual insult to the umpire: "You are, how can I call it ... a small cat."
It was a wild rant from Medvedev and one that tennis fans have got used to witnessing over the years.

'Tsitsipas sick to his shoes' - Medvedev wins thrilling opening set

The Russian has been labelled the "heavy favourite" for the title by Eurosport expert Mats Wilander from the outset of the tournament at Melbourne Park.
The winner of this second semi-final will take on 2009 champion Rafael Nadal, who is seeking a record-breaking 21st Grand Slam title to move ahead of rivals Roger Federer and Novak Djokovic in the GOAT-chasing tally.
Earlier in the day, Nadal swept past Matteo Berrettini to secure his place in the showpiece match on Sunday in style with emotional celebrations marking his improbable journey back to the top.

Highlights: Nadal closes on 21st Grand Slam title by beating Berrettini to reach final

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