Chris Evans thinks no one else could ever play Iron Man except for Robert Downey Jr.

Downey, 52, kick-started the Marvel Cinematic Universe with the 2008 movie 'Iron Man' and has since reprised his role in six films and is set to return in 'Avengers: Infinity War' and 'Avengers 4'.

However, like his co-star Evans - who portrays Captain America - both their contracts are coming to an end after the end of 'Avengers 4', but Evans has nothing but praise for Downey.

Speaking to, Evans said: ''It's low-hanging fruit to say [Robert] Downey. He's such a wonderful guy and is so talented, so experience, and so supportive. He's always been in my corner and I've always felt supported by him. He really brings everybody in to the group and makes sure everyone feels welcome, especially on this last one. He really just opens his arms and it sounds so cheesy, but he makes it a family and none of this would happen without him. No matter what it feels like for me, I try to imagine what it feels like for him, because he really did start this. He really is so irreplaceable. Nobody can ever be Iron Man. It's not a role like Superman or Batman that can kind of find different incarnations, no one can touch it.''

'Avengers: Infinity War' will see the hero squad, which includes Iron Man (Downey Jr.), Captain America (Evans), Thor (Chris Hemsworth), The Hulk (Mark Ruffalo), Scarlet Witch (Elizabeth Olsen), Vision (Paul Bettany), Black Widow (Scarlett Johansson) and Hawkeye (Jeremy Renner), join forces with the 'Guardians of the Galaxy' troop to save the Earth.

The two teams will have to work together to fight intergalactic tyrant Thanos, but they will also receive a helping hand from Spider-Man (Tom Holland), Black Panther (Chadwick Boseman), Dr Strange (Benedict Cumberbatch), as well as Captain Marvel (Brie Larson), which will mark the 28-year-old star's debut in a Marvel production.

'Avengers: Infinity War' is slated to be released on May 4, this year.