Nick Kyrgios' mature performance against Brandon Nakashima has been described as the outlandish Australian's best display to date after the 27-year-old reached his first quarter final in seven years.

Kyrgios advanced to the last-eight after a gutsy five-set victory over his American opponent, coming through a shoulder concern to continue his remarkable Wimbledon journey.

The Australian bad boy was involved in a spiteful match against Stefanos Tsitsipas on Saturday night, with the No 4 seed labelling Kyrgios 'evil' and 'a bully' after his fourth round exit.

Monday's win, then, provided a much-needed tonic to the bitter antics over the weekend, and experts on The Tennis Podcast have lauded Kyrgios for his calmer approach in the last-16.  

'Who knows what will happen over the next few days but he has already done things this week that I didn't really think he could do. I didn't have much belief he could do,' pundit Matt Roberts said.

'He's beaten a top 5 player over five sets, he's won when there was a circus, he's won when there wasn't a circus, he's backed up a real emotional high against Tstispas and won the next match. that's so important in slams. 

'That's how you win slams, by backing it up and doing it over and over again. He's never really demonstrated that he can do that and he's also won when he was a set down - he's done that three times.'

Co-hosts David Law and Catherine Whitaker endorsed Roberts' view, labelling the victory over Nakashima one of the biggest of his career. Specifically, the 'boring' nature of his win was 'exactly what he needed'.

Barring a spat with a journalist over his post-match attire, the Australian's press conference featured very little drama, leaving the experts baffled as to what the 'real' Nick Kyrgios entails.  

'It was a grown-up press conference and I always come out of those going, which (Nick Kyrgios) is the real one?,' Law said. 'They're all him aren't they. This is in him, that's in him. But I don't know whether he knows or is able to control which one of them he is at any given time.

'He was talking throughout that press conference about 'the process' and that's as professional sounding as I've ever heard Nick Kyrgios. In terms of his interest in terms of trying to get the most out of himself at this tournament and seeing how far it takes him.

'All the things everybody's saying they'd wish he would do for the last seven or eight years, he's at least saying he's trying to do.'