Jose Mourinho says Chelsea will keep going after striker Wayne Rooney until the moment the window shuts.
Mourinho intends to test Manchester United's resolve to retain Rooney before the September 2 closure of the transfer window despite Chelsea twice being rebuffed with bids in excess of £20million.
"You try, because nobody forbids you to try," said the self-proclaimed Special One, who could up the stakes for Rooney ahead of the United clash, if he is feeling mischievous.
"When you think that you'd like to have one player and the market is open and the official bids are not forbidden, official bids are always accepted in an ethical way.
"Of course, the player's owners they can do exactly what we did in relation to David Luiz and Barcelona."
Chelsea rejected an approach from Barcelona for Luiz, who is out of tonight's clash with Villa with a hamstring injury, but could return at Old Trafford.
Mourinho would not be drawn on whether he expects Rooney to play against Chelsea.
"I have no idea," said Mourinho, who has plan Bs and Cs in place if Rooney's signature remains elusive.
"If you are speaking about Wayne, it's his decision, it's David's decision, it's their decision. It's not my decision."
For now the Portuguese's focus is on Villa, who beat Arsenal 3-1 last Saturday and were beaten 8-0 on their most recent trip to Stamford Bridge.
Mourinho is wary of Villa following their win at Arsenal.
"They are a team with qualities to play away, to play the counter-attack game they played at the Emirates," he added.
But if the opportunity presents itself he hopes his players can sustain their opening half-hour performance against Hull, when they were scintillating, in an ominous warning of a repeat thrashing for Villa.
"We want to win matches, but what I like is that when you have the chance to destroy, to beat them by three, four, or five," Mourinho said.
"If someone has the chance to do it to you, they will not forgive you, they will give you nothing. "If someone feels that they can do it to us they will do it - when you are in trouble, they smash you - so if we have the chance to do it, we have to do it. That is football."