Earlier in the summer Mourinho claimed Rooney was his only transfer target, and the Blues have since had two bids rejected for the 27-year-old. United has not wavered in its insistence that the England international is not being sold, and Mourinho has now admitted he has other options as he looks to bolster his attack.
"We have Plans B and C," Mourinho told reporters. "Don't ask me names. It's difficult to speak about players from other clubs.
"We have the conditions to try to improve our team by bringing in one more player, and we are going to try that till the end."
Samuel Eto'o has been heavily linked with a move to Stamford Bridge in the past week, having been among a number of players told they can leave Russian side Anzhi Makhachkala this summer.
But Mourinho insists he will not give up his pursuit of Rooney until the transfer deadline, despite United's bullish determination to keep their prized asset.
"You try, because nobody forbids you to try," Mourinho said. "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 can do exactly what we did in relation to David Luiz and Barcelona."