Ferguson is refusing to rush back his star striker too soon although he believes Rooney could make the Montenegro game and will leave the decision up to England coach Fabio Capello.
"Wayne trained on Thursday and he wants to play on Saturday," said Ferguson.
"But I have to take the view that this injury has been niggling away for a while and he kept on playing.
"I have to be dead sure that I am doing the right thing because Wayne has not been doing himself justice.
"I think in a week he will be fine. Obviously we don't play in a week, so it is up to Fabio Capello whether he wants him to.
"The Montenegro match is another 10 days away and by that time I would expect Wayne to be 100%."
Rooney's sole striker for United this season was a penalty against West Ham and he also endured a disappointing World Cup, failing to score as England exited in the last 16.
He did net on his last England appearance, however, the 3-1 Euro 2012 qualifying win over Switzerland in September.
And Rooney: "You always want to play well and give your manager no excuses to leave you out. I want to play every game and never want to be left out but that's the manager's decision.
"But you know that being at a top club like Manchester United there are top players there so you want to be at your best to keep your spot.
"All players get left out at some stage but I'm pretty confident my form will be back to where it should be."
Rooney's England availability for the Montenegro game would be a huge boost to Capello, considering he is unable to select midfielders Frank Lampard and Theo Walcott and strikers Jermain Defoe and Bobby Zamora because of injuries.
Newcastle striker Andy Carroll has been tipped to win his first call-up to the senior squad after he was left out of Stuart Pearce's Under-21s.
This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.