Keane placed himself in the centre of a storm on Monday with his boast that he "had waited long enough" to gain retribution in his apparent feud with the Manchester City player.

Two British newspapers are serialising the Irishman's autobiography, in which his tackle on Haaland in a derby game in April 2001 is discussed.

Now Ferguson, speaking from Hungary ahead of Manchester United's Champions League game against Zalaegerszeg, has entered the row in order to defend his man.

"I don't think Roy has anything to worry about. I don't think there's a case to answer. I don't think there's anything wrong with the book whatsoever," said the Old Trafford boss.

Haaland was left with damaged knee ligaments after the tackle and has not started a game since.

Keane also admitted standing over the Norwegian to taunt him after the foul - for which the United player was sent-off.

The Football Association has already said it will be reading the book, with action possible, and Manchester City have "noted" the comments admidst talk of Haaland suing Keane.

On Tuesday, a Greater Manchester Police spokeswoman said the force "will investigate" if Haaland makes a complaint to them.

But Ferguson has tried to head off any action against the former Republic of Ireland skipper.

"We have never complained when Haaland has made comments about Roy throughout the last few years," said the Scot.

"Every week, or at least every time we played against (Haaland's former club) Leeds United or Manchester City, he would make some comment or other about Roy.

"It's probably something that they (the FA) will look at, but I don't see anything wrong.

"There has been a bit of to-ing and fro-ing between Haaland and Keane in the past three or four years, particularly from Haaland who has had plenty to say."