He could start alongside Suarez in Sunday's eagerly-anticipated Old Trafford showdown, but Ferguson feels his ability cannot be taken for granted.
"The big issue for Liverpool is whether they include new signing Daniel Sturridge," Ferguson told United Review.
"Certainly the arrival of Sturridge gives Brendan Rodgers more strength and options up front.
"Sturridge has had a few clubs but I don't blame him for jumping at the chance of joining Liverpool because he just wasn't playing regularly with Chelsea and I always rate a player whose priority is wanting to play.
"Even so, his track record moving between a number of clubs suggests Brendan Rodgers is taking a bit of a gamble, but he clearly knows what he is doing."