Alex de Minaur has been forced to pull out of the Australian Open with an abdominal injury.

Key points: Alex de Minaur sustained the abdominal injury during the ATP Cup last week

Alex de Minaur sustained the abdominal injury during the ATP Cup last week He had pulled out of this week's Adelaide International to help his recovery but decided he would not be fit in time to play the Australian Open

He had pulled out of this week's Adelaide International to help his recovery but decided he would not be fit in time to play the Australian Open De Minaur had been aiming to advance beyond the third round at the Australian Open for the first time in his career

De Minaur, Australia's top-ranked male player at number 21 in the world, suffered the injury during last week's ATP Cup tournament, in which he played five matches in nine days.

The 20-year-old had pulled out of the Adelaide International on Monday in a bid to be fit for the first major of the season.

"It's not great, I'm [not] going to lie," de Minaur told a media conference.

"Obviously it's a week of the calendar that I really look forward to and put in all the hard work for, so it's pretty devastating to miss out on my home Slam.

"I wanted to go out there and play, even though I've got a four-centimetre grade-two tear. So it's not a joke, it's something really serious.

"Getting out of bed hurts, everyday activity, it hurts. So I was being optimistic … everyone was telling me not to play. It is the smartest thing."

De Minaur reached a career-high ranking of 18 during 2019. ( AAP: Julian Smith )

De Minaur, who reached the third round at Melbourne Park last year, said its was the "right decision" to withdraw from the Australian Open and he would need to reassess his playing schedule in the future.

"The risks of me potentially playing … was that it could obviously get worse, get to sort of a grade-three tear, which involves stitches, and that means probably a problem for the rest of your career," he said.

"It's something to do with workload, especially because it only happens at the start of the year. And especially in the first weeks.

"After that I'm able to play throughout the whole year perfectly. So it's something me and my team have got to look at.

"As tough as it is right now, I've got to learn from what's happened and decide on different alternatives for next time."

Australia's number two, Nick Kyrgios, told his "little bro" to keep his head up and "we are all behind you".

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Kyrgios partnered de Minaur at the ATP Cup, where Australia reached the semi-finals before bowing out to Spain.

At the ATP Cup, de Minaur won two singles matches and an epic doubles decider with Kyrgios, before pushing world number one Rafael Nadal all the way before losing in three sets, 4-6, 7-5, 6-1.

De Minaur has never progressed past the third round at his home major, but was expected to do well after a breakout year in which he reached a career-high of 18 in the world and won his first three ATP titles in Sydney, Atlanta and Zhuhai.

He suffered a similar injury ahead of the 2018 tournament, where he was beaten in the first round by Thomas Berdych after reaching his maiden ATP final in Sydney in the build-up.