Ruthless world No.1 Carlos Alcaraz has revealed the glaring mistake Alex de Minaur made after the local was bundled out of the Australian Open in straight sets.

Spaniard Alcaraz comfortably won the pair's quarter-final clash on Tuesday night, and speaking post-match, he offered some feedback for the deflated Sydneysider.

'When he's playing against the best or the top player, he's trying to be more aggressive, which sometimes (means) he's out of his comfort zone,' Alcaraz said after his 7-5, 6-2, 6-1 victory over de Minaur.

'Sometimes we're seeing him miss quite easy balls, let's say.

'I notice that and we (coaching staff) know how to approach the match.'

It comes as de Minaur has lost his first seven Grand Slam quarter-final appearances and is the third man in the Open Era to do so, after Andrey Rublev and Tommy Robredo.

The Aussie remains a clear level below Alcaraz and world No.2 Jannik Sinner, with a combined 0-19 head-to-head record against the two big guns on the circuit.

Tuesday's comprehensive defeat was his sixth in as many meetings with Alcaraz.

'I'm playing out of my comfort zone and at times out of my skin,' a despondent de Minaur said.

'Of course, for me to take that next step, I've got to be comfortable playing that sort of way for the whole match.

'That's what it takes to take it to the next level, especially against these types of guys.

'It (losing) doesn't feel amazing, I'll tell you that. You try and do the right things, you try to keep improving.

'But when the results don't come or the scoreline doesn't reflect those improvements, then of course you feel quite deflated.'

The world No.6 pointed out his aspirations at Melbourne Park have been cut short by some significant players in recent years - Rafael Nadal, Novak Djokovic, Sinner (twice) and now Alcaraz.

'I'm not losing many matches I possibly shouldn't,' he added.

'You've just got to keep on moving. It's the only way. As tough as it is when you get results like this, you get back up.

'You get back on the horse and that's it.'

Alcaraz, 22, has already won six majors, with the Australian Open the one Grand Slam to so far elude him.