The protests started at the team hotel with around 1,000 supporters outside the Lowry Hotel where the United team were staying.
The game, which kicks off at 11.30 a.m. ET, is likely to go ahead as the Premier League said COVID-19 protocols have not been breached as the supporters didn’t reach the dressing rooms.
A group of United’s coaching staff were turned away from the gates as a result of the number of supporters at the ground.
Two police vans were positioned at the gates used by the team coaches from early on Sunday morning.
Fans started gathering on the forecourt at Old Trafford from around 8 a.m. ET. At around 9 a.m. ET, a large group broke the fencing around the stadium and moved the protest towards the Munich Tunnel underneath the Sir Bobby Charlton Stand.
The anti-Glazer movement has gained momentum in recent weeks following the club’s failed attempt to form part of a breakaway European Super League last month.
The club was bought by the American Glazer family for £790 million ($1.1 billion) in 2005.
Although it has been listed on the New York Stock Exchange since 2012, the Glazers retain majority ownership.
Information from Reuters and ESPN correspondent Mark Ogden was included in this report.