Already one set to the good but serving to level the second set 2-2, Medvedev angrily remonstrated with umpire Mohamed Lahyani after two contentious calls during a game he eventually lost after having led 30-0.
"You guys (the officials) are getting ridiculous," shouted Medvedev at the umpire during the change of ends after he had gone on to lose his service game despite being up 40-15.
He was also seen hitting the canopy covering his seat as he shouted and swore at Lahyani.
The first contentious moment was a deep return by Monfils, which was called out by the line judge on the baseline. The chair umpire came down to inspect the mark and awarded the point to Monfils despite Medvedev having hit a winner from the ball in question.
On the next point, another deep return from Monfils was called good this time by the line judge, but Medvedev stopped believing the ball to be long and, after another verification by Lahyani, the shot was adjudged out.
Medvedev then began shouting at the line judge in question.
"Daniil please don't shout at him," Lahyani said. "He (the line judge) can make a mistake as well."
Despite being 40-15 up in the game, Medvedev went on to lose his service game and fall 3-1 behind in the second set.
The 2021 US Open champion refound his composure later in the set and won five consecutive games to claim his clay court season opener 6-2, 6-4. After the match, Medvedev shook hands with Lahyani but wrote "in or out???" on the lens of a TV camera as he left the main Rainier III court.
Medvedev will next go head-to-head with fellow Russian Karen Khachanov in the third round, with either Alexander Zverev or Stefanos Tsitsipas waiting in the last eight.
