UPDATE: Matt Damon was at the red carpet premiere of his upcoming historical action drama Monuments Men, when he opened up to ET about Hoffman and his passing.
"He was an incredible, incredible human being. And everybody knows that he was an incredible actor. One of the greatest of this or any other generation. And that gift is still with us. He left that with us," Damon said.
Check out the video for the rest of Damon's comments about the Oscar-winners tragic death.
In 1999, Matt Damon, Gwyneth Paltrow and Jude Law got the chance to star alongside Oscar winner Philip Seymour Hoffman in the crime drama The Talented Mr. Ripley. Following the sudden death of the actor, he was only 46, on Sunday afternoon, Damon mourns the loss of his former co-star, telling Good Morning America on Tuesday that Hoffman was "one of the best actors that ever lived."
RELATED PICS: Remembering Philip Seymour Hoffman In Photos
During his interview on the morning show, Damon referred to Hoffman as a "beautiful person" and said the reports that his co-star probably died of a heroin overdose are "horrible."
RELATED VIDEO: Hoffman at Mr. Ripley Premiere
Meanwhile, Damon's co-star Gwyneth Paltrow shared a memory of the beloved actor, posting on Instagram: "Ischia 1998, post dinner, post shooting...Philip was a true genius. #philipseymourhoffman."
Click HERE for more celebrity reactions to Hoffman's tragic death.