Croft only returned to domestic action after a serious neck injury on 4 January and his participation in Leicester's victory over Sale at the weekend was the first time he has played back-to-back matches this season.
Fly-half Farrell suffered a thigh injury against France and although he will miss the Italy game he should be fit to face Wales in the final match of the tournament and potential title decider.
On Farrell's prospects, coach Stuart Lancaster said: "We're pretty sure he will be alright for the Wales game but we don't want to risk that kicking action early in the week.
"It's fair to say that you can read into that that Toby Flood will be starting (against Italy). We need to make a call early to give Toby a chance to settle in."
After Saturday's Aviva Premiership match Tigers coach Richard Cockerill pronounced Croft fit and ready for international duty.
And Lancaster has wasted little time in calling Croft up, at the same time giving the flanker's chances of being named in this summer's Lions squad a huge boost.
Lancaster has a selection poser at No 6 where three different players have been used in this year's Six Nations - and he may be hoping the experienced Croft is the answer.
Tom Wood started against Scotland, James Haskell against Ireland, and Courtney Lawes in the last match against France.
Wood was moved to No 8 following an injury to Ben Morgan, and the Northampton man has been outstanding there so Croft has a chance of featuring in the Italy match.
Lancaster said: "We had Tom in the Six Nations last year and he was one of the stand-out players.
"The injury happened after that and he missed the South Africa tour (last summer) and the autumn internationals. He's been out a long time. But he's one of the few Lions we've got in our team.
"He's a great line-out option, he's a great ball carrier and defender, and he's a leader, most importantly from our point of view.
"He's got a lot of things to get up to speed with - line-out systems and structures, the way we attack and defensive systems but he's an intelligent rugby player."
Source : http://www1.skysports.com/rugby-union/news/12504/8540681/Leicester-star-Tom-Croft-called-into-England-squad-Owen-Farrell-ruled-out
