Daniil Medvedev once again set himself right in the middle of a controversy, this time with an unusual outburst at chair umpire Mohamed Lahyani at the 2025 Shanghai Masters. The Russian even invoked the retired Rafael Nadal in his off-the-rails tirade after being given a code violation.Medvedev took on Learner Tien in the quarterfinals on Wednesday, their third meeting this year. In both previous occasions, the American had prevailed, leaving his opponent with a mountain to climb mentally in Shanghai.Daniil Medvedev started off well enough, taking the opening set in a tiebreaker and then taking a 3-0 early lead in the second. However, ghosts of his previous losses returned, as the former World No. 1 ended up losing the break advantage and forced the set to end in a tiebreaker again.This time, Tien capitalized, breaking away with a mini break. It was here that Medvedev crumbled, resulting in his fury at umpire Lahyani, who thought he was taking too long on the return when Tien was ready to serve.After the violation was handed, Medvedev snapped back at Lahyani, recalling all the times he faced Nadal. The Russian was of the opinion that Nadal had always made the opponent wait, but got no code violation like the one he got in Shanghai. He threw the accusation at the chair umpire's face, calling him 'crazy' for the decision to give him the violation."All my life, I've been serving & waiting for Rafa for 55 seconds. And you give me a code violation on the first occasion. I played Rafa 5 times, there was not one time I was ready to serve and he was ready to return. He didn't get one time violation. To me, today, at the slightest thing you give it to me. I always waited to return, and you didn't give it to him. You're crazy. Completely crazy," Medvedev said.Medvedev went on to lose the set, but bounced back to take the third set 6-4 to reach the quarterfinals of the Masters 1000 event.Daniil Medvedev to take on Alex de Minaur next at Shanghai Masters2025 Shanghai Rolex Masters - Day 10 - Source: GettyFollowing his win over Learner Tien, Daniil Medvedev will next take on Alex de Minaur in the quarterfinals of the Masters 1000 event. The Aussie beat Nuno Borges in the Round of 16, and is yet to lose a set at the tournament.A win against De Minaur would pit Medvedev against either Felix Auger-Aliassime or Arthur Rinderknech in the semifinals, with a potential final against Novak Djokovic looming.