'Not happy': Nick Kyrgios fumes at umpire after split-second moment

Nick Kyrgios has ripped into the chair umpire after a controversial point went against him during the Canadian Open on Tuesday.

The 26-year-old was defeated by America’s Riley Opelka 4-6 7-6 6-4, his third straight defeat as he looks to prepare for the upcoming US Open.

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The hardcourt swing hasn't been kind to Kyrgios and his run of bad luck continued in Toronto.

It was during the crucial second set tiebreak, which Opelka eventually won, that things began to go off the rails.

Kyrgios was left fuming with the score at 4-4 after his claim that Opelka had touched the net with his foot was dismissed by the chair umpire.

The furious Canberra native was not having it, launching into a classic diatribe.

“What are you watching? I saw his foot touch the net and you’re not going to call it,” Kyrgios called out.

“What else could you be watching, bro? I can see his foot touch the net from where I am, and you don’t call anything.

"It’s a joke, bro. It cost me the f***ing set. Bulls***.”

Kyrgios earned some jeers from the crowd a short while later when his temper got the better of him and he launched a ball into the stands.

The moment was a clear turning point for Kyrgios, who had looked confident in the first set after struggling at both the Washington and Atlanta open tournaments.

Nick Kyrgios questions his competitive fire ahead of US Open

After admitting he often wondered whether it would be worth retiring from tournament to tournament, Kyrgios simply didn't have it in the first round of the Citi Open in Washington D.C.

Kyrgios appeared somewhat frustrated but didn't succumb to what some might consider a 'typical' outburst - something he confessed after the game might have been required to sufficiently fire him up.

Instead, he went down to Mackenzie McDonald 6-4 6-4, with one underhand serve the only taste of Kyrgios's individual flare the crowd witnessed.

Speaking to media after the game, Kyrgios lamented his lack of energy.

"I don't know what it is. I don't know what to say. I don't know how to feel. I just don't feel as if I'm in the moment as I used to be, I guess," Kyrgios said.

"I feel like I actually enjoyed my tennis more when it was so up and down. Like you see me today - like, I'm losing and I'm barely getting angry.

"I actually miss the days when I was losing and I was carrying on and I was getting fined and I was throwing my rackets."

Despite questioning his own motivations afterwards, Kyrgios appeared to be quite chipper throughout the match, even continuing his recent habit of requesting fan advice as to where to place his serves.

He hinted that perhaps the firebrand of old, which was determined to be as prickly towards opponents as possible, might need to return in some way shape or form for him to reach the heights many believe he can.

"Now I lose and I'm actually happy for the other guy," he said.

"Back then, I couldn't stand the other guy."

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