As well as the cross-city derby, which will open the season at Melbourne Arena on Thursday night, the injured pair won't return until at least round three.

United coach Dean Vickerman confirmed big man Barlow was out with a fractured thumb while forward Prather was ruled out later on Wednesday with a knee injury that requires surgery.

American Prather, who helped United win their 2017-2018 title, before spending last season in Europe, has a history of knee trouble.

Scans have revealed that Prather will require minor surgery that will see him miss up to three weeks, the club said in a statement.

With Prather sidelined, Melbourne has signed local Dillon Stith as an injury replacement player.

Stith is coming off a BigV season in which he led the McKinnon Cougars to the Championship Men title and collected league MVP honours.

Vickerman said 35-year-old Barlow also won't travel to Perth for Saturday night's game against the Wildcats or to the US for their NBLxNBA games against Los Angeles Clippers and Sacramento Kings.

Kiwi Tohi Smith-Milner and NBL debutant Jo Lual Acuil are set for more game time before Barlow returns in round three.

"Everyone has played in our league except Jo and every time he has had a chance to play 20 minutes or more in pre-season he has averaged about 18 (points) and eight (rebounds)," Vickerman said.

"He's going to play good minutes tomorrow and Tohi is playing the best basketball we've ever seen from him.

"Great world championships and he followed that form with a great game in Adelaide."

Vickerman predicted South East Melbourne, led by Boomers star Mitch Creek and coached by former United assistant Simon Mitchell, would be keen to make an opening statement.

"They've had a year to plan for this game and Simon's a really detailed coach who would have done a great job in scouting us," Vickerman said.

"There's a lot of scoring on that team, a lot of shooting, and how well we can disrupt that will play a big part."

Australian Associated Press