Former world number one Daniil Medvedev was once again drawn into a heated exchange with an umpire before crashing out of the Monte Carlo Masters following a 6-3 7-5 defeat by fellow Russian Karen Khachanov in the last 16 on Thursday.
Fourth seed Medvedev, who had reached at least the quarter-finals in the last two editions at Monte Carlo, never truly got going against Khachanov.
After a topsy-turvy start with four breaks in the first four games, Medvedev double-faulted to gift Khachanov the lead at 5-3, with the world number 17 holding serve comfortably to clinch the opening set.
Medvedev shook off some of his early rustiness in the second and had set point when he was 5-4 up, but squandered that opportunity and was unable to break Khachanov's serve.
Khachanov's hold under pressure proved the final straw for Medvedev, who faded quickly and hurled his racket against the backboard after an erroneous call from a line judge.
"Open your freaking eyes," Medvedev, who also argued with the chair umpire after his win over Gael Monfils on Wednesday, shouted at the umpire and supervisor, before being issued a point penalty.
The win sees Khachanov reach the last eight in Monte Carlo for the first time.
"Mentally, even though I've lost a few hard matches to him on hard courts, I know he doesn't like to play on clay and that gives me some extra confidence," Khachanov said in his on-court interview.
"Sometimes I know Daniil can lose his mind. Sometimes he uses it as a tool, but it can get out of control sometimes. I tried not to look at him or focus on him, and just serve it out."
Earlier on Thursday, 11th seed Alex de Minaur beat Alexei Popyrin 6-3 6-4 in an all-Australian clash.
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