Rovers boss Paul Ince doesn't want to lose his star player but confirmed a bid had been made.
Ince will want at least £17 million for his England winger, which is what Villa expect to receive from the sale of Gareth Barry.
However, the deal for Bentley does not depend on Barry's probable move to Liverpool.
With reported interest from Tottenham, Villa will need to act quickly if they are to secure his coveted signature.
The funds are clearly available but Bentley is known to favour a move to London.
That preference means Martin O'Neill must use his full monetary and verbal persuasion to convince the former Arsenal midfielder his future lies in the Midlands.