The former Liverpool and Real Madrid winger believes the Premier League champions will have their work cut out against the Bavarians in Europe
The reigning Premier League champions were paired with Pep Guardiola's side in last Friday's draw, with the Bavarians firm favourites to advance against a United side enduring the most torrid of campaigns.
David Moyes's men squeezed past Olympiakos in the last 16 courtesy of a 3-2 aggregate victory but are sat seventh in the Premier League table following Tuesday's 3-0 defeat to Manchester City.
And McManaman, who played for United's arch-rivals Liverpool before winning the Champions League with Real Madrid, fully expects Bayern to breeze into the semi-finals.
"Can United beat Bayern? No, they have no chance," he said. "Bayern Munich have an amazing team - they're over 50 games unbeaten which is an incredible record. They are the favourites for the Champions League."
The 42-year-old then gave his thoughts on the race for La Liga following Barcelona's 4-3 victory over Real Madrid at the Bernabeu on Sunday.
"The result of the Clasico is great news for La Liga because there are now three teams in with a chance of winning the title," McManaman added.
"When I see Diego Simeone with Atletico Madrid I see real possibilities, he is doing a perfect job."