The Marvel blockbuster is out in April, and comes after a long string of hit films in the franchise.
And while Captain America and Iron Man may appeared to have been on the way to putting their troubles behind them, it seems they may still face off once more.
Robert Downey Jr, who plays the latter, told USA Today: “That’s the hardest for me, because I look at Evans and I just to want to go over and smell him or tell him he looks cool in those sunglasses when he’s walking over to have lunch.
“And then I’m just staring daggers at him, getting mad.”
He added: “But even that relationship is going to take a turn.”
Avengers Infinity War will boast an enormous cast, including Mark Ruffalo as Hulk, Tom Hiddleston as Loki, Chris Evans as Captain America, Scarlett Johansson as Black Widow, Elizabeth Olsen as Scarlet Witch, Chris Hemsworth as Thor and many more.
Not all of the established regulars are expected to survive Infinity War and its as-yet-untitled follow-up – and actually it’s Downey Jr who has been among the most hotly tipped to make an exit.
Johansson has also indicated that her time in the MCU may be drawing to a close, saying: “It’s bittersweet to imagine not having these films to come back to.
“I’ve been living this story with these people for 10 years through ups and downs.
“We’ve built a great family. Personally, it feels like a loss.”
Avengers Infinity War is out on April 27 in the UK.