The France international is thought to be facing an uncertain future at the Red Devils in the summer transfer window.
Martial has been linked with a potential switch to Premier League title rivals Chelsea FC and Tottenham Hotspur.
The 22-year-old has also been attracting interest from Bundesliga giants Bayern Munich and Borussia Dortmund.
Martial struggled to hold down a starting spot in the Manchester United team in the 2017-18 season.
The France star has fallen further down the pecking order following the arrival of Alexis Sanchez in a swap deal from Arsenal.
Former Manchester United defender Brown delivered his blunt verdict on Martial’s current situation at Old Trafford.
“I like Anthony Martial. I think he’s a great talent and he’s young. But he’s not been playing so maybe he and the manager don’t get on and maybe he’s not listening to what the manager is asking,” said Brown, speaking exclusively to 888sport.
“Ultimately that’s what the players have to do. You have to listen to your manager. He didn’t play many times last year so looking from the outside it doesn’t look good. He might be off.
“If someone is having a kid then you like to think the manager would say ‘yeah, you can go for that’ and if it was me I’d want to go. But I’d have come straight back.”
Mourinho has signed Shakhtar Donetsk midfielder Fred, FC Porto defender Diogo Dalot and veteran England goalkeeper Lee Grant to improve their squad ahead of the new season.
Manchester United lost 1-0 to Chelsea FC in the FA Cup final at Wembley last term following Eden Hazard’s winner from the penalty spot to finish the season without silverware.
The Red Devils won the Europa League and the League Cup in Mourinho’s first season in charge at Old Trafford.
Read the full 888sport interview with Wes Brown, including his thoughts on Paul Pogba being ready to step up a gear this season.
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