Nick Kyrgios has withdrawn from the Australian team for the inaugural United Cup due to injury, less than 24 hours before the start of the tournament.

World number 22 Kyrgios was due to lead the Australian charge against Great Britain in the team's opening Group D tie tomorrow evening.

He had been drawn to face Britain's Cameron Norrie in the singles at Ken Rosewall Arena in Sydney.

However, a statement from organisers on social media confirmed that Kyrgios had pulled out of the event.

"Alex de Minaur will move into the number one men's position for Team Australia, and subsequently Jason Kubler moves into the number two spot," the United Cup account tweeted on Wednesday.

Kyrgios was dealing with a niggling injury after training on Tuesday afternoon.

His teammates told media they had only learned 10 minutes before the press conference that Kyrgios would not be joining them for the event.

The decision also robs the tournament of one of its marquee match-ups on January 2, when Kyrgios was due to open Australia's tie against Spain with a blockbuster match against Rafael Nadal. 

The United Cup — along with the second Adelaide International event in January — was due to form part of Kyrgios' preparation for a tilt at a home slam.

Kyrgios was also due to represent Australia for the first time since the now-defunct ATP Cup in 2020, having sat out the Davis Cup for the past three years, as well as the Tokyo Olympics.

ABC/AAP