The in-form attack was surprisingly left on the bench for the Premier League champions’ 1-1 draw with Liverpool on Saturday, as the Scottish coach felt that his international ban for England was playing on his mind.
Despite this, Rooney will play in the fixture in Romania, after being desperate to feature at Anfield.
“He’ll be playing tomorrow,” Ferguson declared in a pre-match press conference.
“When the initial news came through it was a definite blow for him. He didn’t expect that. None of us did.
“It was a silly action but it wasn’t seriously dangerous. When he realised getting a three-match ban meant missing all the games for England and might not be involved at all, it is not easy to qualify in major championships, that resonated in Wayne’s mind.
“But actually, when he came on he was quite bubbly. He was full of energy and enthusiasm.
“He was desperate to get on, which is good. When he was sat watching the game he probably said, ‘Christ I could be out there’,” Ferguson concluded.
Meanwhile, Rio Ferdinand will not feature against the Romanian champions, as he is being rested for the clash with Manchester City this Sunday.
Nemanja Vidic, who has missed all but one game of the campaign so far this term, is in line for a return however, after recovering from a calf problem.
By Gareth McKnight