Andy Murray called it "irritating" and Nick Kyrgios said it was "stupid" as confused players at the Australian Open had to deal with spectators giving them Cristiano Ronaldo's "siuu" celebration treatment. Football fans are used to seeing the Manchester United superstar launch into a mid-air pirouette before exclaiming "siuu" when he scores — which comes from Spanish and Portuguese words for yes. But for the uninitiated it sounds like "boo" and fans at the opening Grand Slam of the year were shouting it en masse during Murray's and Kyrgios's matches at John Cain Arena on Tuesday. Crowd favourite Murray, who came through an epic first-round five-setter against Nikoloz Basilashvili, said he couldn't figure out why people appeared to be jeering him at first. "Initially, I thought it was (jeering), because there were some people booing during my practice yesterday. I have no idea what for, so originally that's what I thought it was," he said. "But then after a few times it was like, no, they're doing that, I think it's like 'siuu' or something that Ronaldo does when he scores. "And, yeah, it was incredibly irritating." Volatile Australian Kyrgios is used to rowdy crowds, particularly when he plays on John Cain Arena — his preferred court at Melbourne Park. But even he found it too much. "Yeah, it's just a stupid (thing), I can't believe they did it so much," said Kyrgios, who breezed through a straight-sets win over Britain's Liam Broady. "They were doing some Ronaldo thing. Ronaldo does it every time he scores. "I thought they were going to do it for like 10 minutes. They did it for two-and-a-half hours, like every point. I don't know why, I don't know. It was a zoo out there."