«He lacks respect for the crowd, his opponent and towards himself.»
He went on to say: «I don’t think he’s a bad guy, but he lacks a little respect for the public and the rival.»
There were several flashpoints in the match which might have upset Nadal.
During the first set, Kyrgios appeared to not be giving a full effort on occasions and even flirted with pulling out of the match.
«I feel sick … if I forfeit, the media will blow it up … I’ll be booed off the court,» he said during the set.
«I’m gonna try to play a couple of more games.»
Kyrgios received a warning for swearing and telling the crowd to «shut up» during the second set.
Nadal appeared to be upset in the tense third set tiebreak when Kyrgios complained to the chair umpire about the 17-time grand slam champion taking too long in between points when Kyrgios was serving.
Yet the quality of play and perseverance couldn’t be questioned.
He saved nine break points throughout the match including coming back from 0-40 positions in the final two sets.
Kyrgios also saved three match points, including one with a lunging volley that hit the net cord and just landed in.
It was Kyrgios’ best win since the Cincinnati Masters in August 2017, when he also took down the then No.2 Nadal in straight sets in a quarter-final.
There might be more controversy ahead as Kyrgios will next play arch-rival Stan Wawrinka.
Meanwhile, fellow Australians John Millman and Alex de Minaur also moved through to the last eight.
Millman blitzed world No.87 Peter Gojowczyk 6-0 6-2, at one stage winning eight games in succession.
The world No.44 converted six break points and delivered the contest’s only two aces to set up a quarter-final clash with third-seed John Isner.
Isner eliminated compatriot Sam Querrey 6-4 6-4.
Fifth seed de Minaur progressed when Feliciano Lopez withdrew before their second-round match. He’ll play Alexander Zverev, a 7-6 (7-0) 6-1 winner over David Ferrer.
Wawrinka beat seventh-seeded Steve Johnson 7-6 (7-5) 6-4.