Australian tennis firebrand Nick Kyrgios has slammed Kazakhstan's Alexander Bublik for an apparent slur that was picked up by microphones during his US Open first-round loss to Dominic Thiem.<br /><br />Bublik went down 6-3, 6-2, 6-4 to the 2020 champion, and during the second set the world No 27 allegedly said in Russian: 'I am f**king sick of giving careers back to disabled people.'<br /><br />It was Thiem's first Grand Slam win in more than two years after struggling with a serious wrist injury.<br /><br />Bublik has also lost to Stan Wawrinka and Gael Monfils recently after they had both returned from absences due to injury. <br /><br />Kyrgios, who is struggling with his injuries at the moment, was quick to comment on the incident, writing on X (previously known as Twitter): 'This is low-key horrible.'<br /><br />Tennis journalist and commentator Jose Morgado also slammed Bublik on Twitter, accusing him of 'a tremendous lack of respect'.<br /><br />When Thiem was questioned about the apparent insult during his press conference, he wondered if the translation was correct.<br /><br />Informed by a reporter that it was, Thiem disapproved of the remark. <br /><br />'It's a tough saying,' Thiem said.<br /><br />'Something you shouldn't say in general, out of respect. Maybe he didn't mean it that way.'<br /><br />Tennis fans were also outraged by the alleged sled from Bublik, who has a history of controversial moments on the court. <br /><br />One fan wrote on Twitter: 'I sometimes can't understand how he manages to escape the criticism and fines that Nick Kyrgios gets. His on-court behavior is just as bad as NK, and he's done and said so many offensive things?'<br /><br />Another replied: 'Bublik says s**ty things practically every other match. This is disgusting even by his standards though.<br /><br />Bublik created headlines earlier in the year when he lost all composure and smashed three of his racquets in a stunning on-court meltdown in Montpellier.<br /><br />Thiem will next face young American Ben Shelton in the second round of the US Open.