Bean limped out of the 2-1 win over Brighton on Saturday, which kept Queens Park Rangers in second place in Divsion Two, and will miss tonight's LDV Vans southern area semi-final at Southend. The 19-year-old midfielder will have a scan today and could be out for longer if the damage is serious.
Bean will be replaced by Dean Marney, who is on loan from Tottenham. Rangers are just two ties away from a money-spinning trip to Cardiff and manager Holloway left fans in no doubt that he wants to win the competition.
He said: "Winning is good habit and I want us to win in every game we play. We're going well in the league but this competition is about to get serious and I want to win the game. We're close to a big day out in Cardiff and that's very exciting.
"We'll miss Marcus but I've every confidence Dean can do a good job for the team. He's well thought of at Tottenham and will get the opportunity to get some first-team experience with us."