louis van gaal says manchester united are in race for the premier league .
dutch boss reserved special praise for marouane fellaini 's recent form .
he says that the belgian midfielder has made himself almost undroppable .
united are eight points behind chelsea having played a game more .
van gaal 's charges face aston villa at old trafford on saturday at 3 pm .
robin van persie is still not fit enough to play at the weekend .