Radamel Falcao said that his stay at Atletico Madrid since joining Porto has been "like a dream".
The Colombia forward is set to complete a €60 million switch to Monaco this summer, having helped the capital club win the Europa League, the European Super Cup and the Copa del Rey in a two-year spell.
Falcao is expected in the Principality this week for a medical ahead of completing the deal.
"I'm very grateful for these two years at Atletico Madrid," the 27-year-old told W Radio.
"I never expected to win three titles in so short time, this has been like a dream. Yesterday I lived a very emotional moment I had never lived before with the fans and a club.
"I will never forget it and I don't know how to give them thanks."
However, Falcao refused to confirm that he would leave the club in the summer: "Right now, I can't talk about my future, there will be time later."
Atletico Madrid president Enrique Cerezo also denied a deal for Falcao has been completed: "Falcao is yet Atletico's player. He is going to play a match [against Zaragoza] and after we talk about his future."
Meanwhile, Colombia are set to play Argentina on June 8 as their bid to qualify for the World Cup continues and Falcao is confident his nation can prevail in the clash.
He said: "Colombia have a great team with the capability to play in any field, any time, against any rival but we need to be discreet and think about what can we do against Argentina."