Christos Kyrgios has come to his under-fire brother’s defence, explaining Nick’s sledging was due to an already rocky professional relationship with Stan Wawrinka.

On Wednesday, during a second-round match at the Montreal Masters, Nick Kyrgios linked the reigning French Open champion with teenage Australian player, Thanasi Kokkinakis.

“Kokkinakis banged your girlfriend. Sorry to tell you that mate,” said Kyrgios midway through the second set.

Wawrinka divorced his wife Ilham earlier this year and has since been romantically linked with Croatian teenager Donna Vekic.

“Nick’s not a person that likes to go out there and cause trouble… if you’re going on about your own business and someone has a stab at you… I’m sure you’d probably say something back,” Christos told 3AW radio.

“I’d rather describe him (Nick) as ‘respectful when respect is given to him’.”

Christos alleged the bad blood between the two started after Wawrinka accused Nick of faking an illness in an earlier match.

Christos’ comments come after he was cut-off from an earlier interview with Triple M radio due to an inappropriate comment.

During the interview with Triple M, Christos said of Nick’s sledge: “If you’re going to come and openly, it’s not even sledging, that’s openly slandering someone after a match, then you can expect a bit of sledging back.”

Kyrgios’ mother Nill also came to her younger son’s defence and said on Twitter: “Sledge for a sledge”.

Nill Kyrgios has since deleted her Twitter account.