"I've a good trainer who drags me out of bed early in the mornings. So yeah, it's fun."
In Jason Bourne, the Swedish actress plays CIA agent Heather Lee with expertise in computer hacking. She doesn't get involved in Damon's bare-knuckled fight scenes, but it brings her one step closer to action hero status.
"She was a huge new element for us because she represented this whole new arena of warfare and cyber warfare, and she's also this incredible young actress and a whole fresh face for the franchise," Damon said.
Even Vikander was surprised to be involved in the gritty movie franchise, although the evolution of the movies left space for a modern character like Vikander's.
"I was a big fan of the Jason Bourne movies so I was thrilled when I just heard they were going to make a new one and that was before I even knew that there would be a part available for me," she said.
"When I had a call from [director] Paul Greengrass, I was thrilled. I met him for lunch and he told me about this idea and how the world has now changed so much since the last Bourne movie, and how that kind of brings up new issues and aspects for a world Bourne could be in."
Demand for Vikander, who won the Best Supporting Actress Oscar for The Danish Girl, shows no sign of waning. Last year, she also starred in Ex Machina, Burnt and The Man From U.N.C.L.E. and this year, aside from Jason Bourne, she also has Tulip Fever (with Christoph Waltz) and The Light Between Oceans (starring with her beau, Michael Fassbender).
"I loved working with Alicia, she's great. She's just this dynamo who just exploded on to the scene like really out of nowhere and her work is just awesome," Damon said.
"Everybody wants Alicia Vikander in their movie right now so we were very lucky to get her."
• Jason Bourne opens in New Zealand cinemas on July 28.
- AAP