Gleeson, who plays fur trader Captain Andrew Henry – a man attempting to keep both his men and product safe –spoke exclusively to RadioTimes.com less than an hour after the nominations were announced.
“I think it’s probably, in my opinion, his career best work,” he said of DiCaprio.
“The effect of what he’s done I feel most palpably in the performance, not in how other people respond to it, just in how I responded to it. I think he’s already a phenomenal actor,” Gleeson explained. “He got to a standard I wasn’t sure anybody was capable of, really, with what he did.
“It’s a performance I’ll remember forever.”
“It was such an effort across the board,” Gleeson added, of the film’s multiple Oscar nominations, which also include make-up, production and visual effects to name just a few. “It’s very cool”.
“When I saw the film I just thought that it exceeded even what we set out to do. I just thought the film was worth it. When a film is that much trouble to make, it being worth it is difficult – and I thought it was way more than just worth it. So that made me happy.”
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