Liverpool play Chelsea in the second leg of their semi-final at Anfield on Tuesday without the suspended Xabi Alonso.
The Spaniard's absence had looked costly with the tie level at 0-0 from the first leg, but Liverpool now have experienced German international Hamann to take his place.
"Didi is fit and he will be in the squad for the Middlesbrough game on Saturday," Liverpol manager Rafael Benitez told reporters on Friday.
"His knee was a problem but he has recovered from that now. While he may not be 100 per cent physically, his knee is okay.
"He may
Hamann has not played since limping off in the win over Everton in the Merseyside derby on March 20.
Liverpool need to beat Middlesbrough at Anfield in the Premier League on Saturday to keep alive their hopes of catching fourth-placed Everton.
They have 54 points, four behind Everton having played a game more than their Merseyside rivals.
"We are confident," Benitez said. "We need to win four points more than Everton and the first thing to do is win our next game.
"We can't think we need to win nine points in total. I don't want to be thinking about numbers all the time."