“You want a perfect monologue? Yo, shut up”

on a modest note before shifting into high gear … and then hit a wall.

“I’m just taking this all in. I’m so excited to be here. This is a dream come true, not just for me but for everyone here,” Koy said in opening the CBS-televised show on Sunday night.

Kevin Costner’s here. Kevin Costner’s never here. He’s like on a mountain with a cow or something.”

Koy also joked about the movie epic “Oppenheimer” — “I could’ve used another hour” — and about its star, Cillian Murphy.

“‘Oppenheimer’ answered a lifelong question that’s been on my mind for years — yes, scientists do get laid, as long as they look like Cillian Murphy.”The comic also took aim at the British royal family.

“‘Succession’ has nine nominations. Just a great series about a rich, white, dysfunctional family, all scheming — oh, wait, that’s ‘The Crown.’ I’m sorry.”

Dec. 21, with only 18 days to go until the CBS broadcast.

He referred to his rushed hiring when he turned his attention to Robert De Niro and made a crack about the actor becoming a dad again recently.