Roger Federer has overcome a rare bout of frustration with umpire Fergus Murphy on Rod Laver Arena to take the first set of his Australian Open quarter-final against Tomas Berdych.
The Swiss great, trailing Berdych 3-5 but holding a break point on the Czech's serve, challenged a call but the review system failed to appear on screen.
Murphy informed the players and the crowd that the ball was called in, meaning Federer lost the point and the challenge.
The defending champion, who was down 1-4 at one point earlier in the match, immediately approached the chair umpire.
"He's going to ask for why he's lost a challenge when he didn't get to use one," said Jim Courier in commentary.
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"I think that's a really interesting point. How can you challenge if you don't get to see it?"
Federer remonstrated with Murphy for a time.
"Yeah but you can't steal my challenge now," Federer appeared to be heard saying.
"You feel comfortable doing this? I'm just asking you do you feel comfortable doing this? You feel comfortable, you're ok with it?"
The back and forth continued as Murphy seemingly defended the decision.
"It's your call. You can say 'ok, he's already been screwed over once'," Federer said.
The 19-time major champion walked away from Murphy in disappointment and went on to win the game to level the set at 5-5.
He referenced the argument again later in the set, when he served a double fault and directed a sly line at the chair umpire.
"Can I have another challenge?" he asked sarcastically.
After wrapping up a straight-sets win over Berdych, Federer revealed he quizzed the umpire out of frustration with his performance and said he suspected Murphy was correct all along.
Federer completed his first-set comeback with a 7-1 tiebreak triumph, ending it on a stunning drop shot that fooled Berdych:
While Hawkeye is largely free of errors, the source of Federer's frustration was not the first glitch in the tournament.
Kyle Edmund set up a crucial break in his quarter-final victory over Grigor Dimitrov with this impossibly close review that suffered a monster delay: