"Didi missed between mid December and the end of February and since early May up to now he's been unable to play for the first team because of two operations.
"That means over the last year we had Didi Hamann out for nine months so it's good to see him back.
With the UEFA Cup tie in the balance after a 1-1 draw in Bucharest, Houllier hinted that Hamann could be back in the starting line-up tonight.
"I did not take Hamann to Middlesbrough last weekend, I wanted him to prepare properly for the games coming up," he added.
"We had five games in 15 days, now it is four in 12, so we need all our players.
"His injury is behind him now and he will be able to take part very soon."
How important is Dietmar Hamann to Liverpool?