Katie Boulter's tennis star boyfriend Alex de Minaur warned NOT to 'p*** off' Novak Djokovic ahead of Wimbledon quarter final after Centre Court outburst

Wimbledon favourite Mark Philippoussis believes Alex de Minaur can cause a sensation by toppling Novak Djokovic in his first quarter-final on Centre Court, but smiles it may not be the best idea to make the seven-time champion mad.

Australian tennis greats were upbeat about the 'Demon's' chances of defeating the seven-time champion on Wednesday, but all concurred with former Wimbledon doubles champion Todd Woodbridge's verdict that the Sydneysider will have to pay the 'match of his life'.

Speaking before the invitational legends' doubles at SW19, Philippoussis, the 2003 finalist, declared: 'Of course, he (de Minaur) can beat Djokovic. He's got the game and the mentality to go against anyone.

'He's doing everything he has to do, top 10 in the world, playing with confidence, some of the best tennis of his career, having won a grasscourt tournament already this season, and he's continuing to put pressure on the top guys.

'We know the heart he has and the speed he has around the court, but the good thing is, which I believe is a big part of him getting into the top 10, is he's being more aggressive, which he needed to be.'

But Philippoussis, now 47, couldn't help smiling as he watched Djokovic, after his win over Holger Rune in Monday's last-16 match, then angrily round on the Dane's fans whom he felt were disrespecting him with their chants.

'I saw a little bit of what happened. I could see him on a change of ends doing something, and I was like, 'okay, something's happening, someone's p***ed him off - which is a bad idea. You don't want to piss off Novak!

'I think he wants to hear 'boo', to be honest with you, because it makes him play better. If I were to play him, I would just give him compliments on a change of ends. I don't want to p*** that guy off, that's for sure! 

'That mentality even towards certain parts of the crowd, to be honest, I love to see that. That's the whole part of what he brings to the table.

'It is just something he uses to his advantage. I am not saying that he needs to, but sometimes you just see in his eyes, when he gets focused and agitated for something, he goes to a different level mentally. He just clicks in and he uses that to play better.

'His confidence is growing with every match. His confidence has also grown with his knee (which required surgery a month ago).

'If you want to win a grand slam, you've got to play the best in the world and beat the best - and this guy is that.'

Like the rest of Australian tennis, Philippoussis was alarmed to see de Minaur's muted celebrations, having suffered a hip problem while stretching to play a winning volley on his winning point against Frenchman Arthur Fils.

'It's not the celebration you would think going into a quarter-finals, but I know it's normal for the second week of Wimbledon to be feeling niggly things on your muscles,' said the big-serving player