The R's midfielder from Cameroon believes new boss 'Arry can lead rock-bottom R's to safety in 2013.
Mbia said: "The manager will enable the players to give their best.
"I believe in him - he is the man to get us out of trouble.
"He has helped me a lot already and tried to make me a more intelligent player.
"The most important thing is to follow what the gaffer says, that is the only way we can move forward."