Johansson was all smiles as she showed some serious leg while walking arm in arm with her man, who dressed to the nines in a flawlessly tailored grey suit. The actress also sported a custom gem-adorned hand chain, created by Sonia Boyajian, that channeled Thanos' Infinity Gauntlet, similar to Brie Larson's bauble homage.
ET's Kevin Frazier spoke with Johansson at the star-studded premiere, and she jokingly explained how she plans on using her contacts at the show (i.e. her boyfriend) to mess with Rudd when he takes center stage in Studio 8H.
"I've got connections. I'm gonna make sure that his time is really difficult, you guys," Johansson explained. "I'm gonna sabotage him. I'm gonna come in from the inside [so] he doesn't know what's coming."
Addressing the camera directly, Johanson jokingly issued a warning directly to her Avengers co-star: "I'm coming for you, Paul! Watch out!"
This will be Rudd's fourth time hosting the late-night sketch comedy series. Johansson herself has hosted the show five times, most recently in season 42 in March 2017.
ET also spoke with Rudd about his upcoming SNL stint. "I'm really excited about that season finale. I've hosted it, this will be my fourth time hosting and it's terrifying every time but really exciting," the 50-year-old actor dished. "I'm looking forward to that."
As for Johansson, who once again plays S.H.I.E.L.D. agent and world class spy Black Widow in Endgame after surviving the genocidal snap at the conclusion of Infinity War, she will soon be starring in her own Black Widow spin-off, but the 34-year-old actress had to stay mum about the project entirely.
"My lips are sealed. I am under lock and key," she said. "I would like to talk about one thing I do professionally but it's not gonna be with Marvel. That's just the way it goes."
Fans can see Black Widow in action when Avengers: Endgame hits theaters on April 26, but in the meantime, here's more with Rudd: