Mum's the word! Jeremy Renner was a guest on Late Night With Jimmy Fallon on Wednesday, Jan. 17, just hours after Us Weekly exclusively revealed that he's going to be a first-time dad imminently -- with a pregnant ex-girlfriend expecting to give birth in February.

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But the Oscar-nominated actor, 42, didn't discuss the baby news during his sit-down with Jimmy Fallon. Instead, Renner (greeted with happy squeals from female fans in the audience) was all smiles chatting about his night at the Golden Globes in Beverly Hills this past Sunday. "I presented," Renner told Fallon. "It's actually fun being at that awards show -- no responsibility besides saying a sentence!" PHOTOS: Sexy celeb dads

Indeed, it was at that all-star bash that Renner confided in pal Eva Longoria about his baby-to-be, two witnesses told Us. "He was saying 'I'm going to fly in when her water breaks.' Then Eva said, 'I'm so blown away.'" (Two insiders confirm to Us Weekly that an ex of Renner's is currently staying at the star's L.A. home as she awaits their baby's birth. "They used to date but it wasn't serious," one source explains.

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But Renner was all business -- but very jovial -- on Fallon as he promoted his upcoming action-adventure fantasy film, Hansel and Gretel: Witch Hunter, inspired by the classic fairy tale. The titular siblings are grown up and "pissed off" in the movie, he explained. "They were left in the forest to die and a witch tried to eat them and they killed the witch -- that was the end of Hansel and Gretel the fable."

Fallon also teased the hunk about the wispy mustache sported during the Globes. "It was a last-minute decision--it took me three weeks to grow!"

This article originally appeared on Jeremy Renner All Smiles on Jimmy Fallon After Baby News