Nick Kyrgios has fired a shot at Pat Rafter in defence of fellow player Bernard Tomic, accusing him of being "negative" after Rafter returned serve to Tomic's verbal outburst following his exit from Wimbledon.

Kyrgios took offence at Rafter's comments in News Corp papers on Sunday and took to Twitter to voice his disappointment.

Needs to find a balance: Nick Kyrgios. Credit:Getty Images

"Another negative comment out of Rafters mouth," Kyrgios tweeted. "Does this guy ever stop #everyoneisaworkinprogress."

The tweet has since been deleted.