The Inter attacker departed the Calderon last summer but is still a keen follower of the Rojiblancos and is desperate for them to beat Athletic Bilbao in Wednesday's match
The capital outfit convincingly defeated Valencia over two legs at the semi-final stage a fortnight ago to reach their second European final in three years and set up an all-Spanish clash with the Basques.
Forlan played a major role en route to Atleti's success in 2010, as he scored twice against Fulham in the tournament decider to win his team the trophy, and he admits he is holding out for them to repeat their triumph.
"I'll be rooting for Atletico; I am their fan even more now," Forlan was quoted as saying by Internews.it.
"I hope we [Atleti] can rewrite history, I have great memories of my experience there and even now when I see people from the club, they still welcome me.
"I remember the final two years ago, and it was really something excellent and unforgettable."
Kick-off in Bucharest is scheduled for 20.45CET.