"I'm extremely flattered by it," Will told Access Hollywood during an interview to promote his new film, "Land of the Lost," on Saturday.
Will, a California native, was Conan's final guest on "Late Night" back in February, and it was more than coincidence that he is Conan's first "Tonight Show" guest this evening.
"We kind of had to keep it under our hat," Will said of the planning that went into his guest slots. "They asked a long time ago, which was so nice… Back in January they asked."
Will said he's pleased to see his 46-year-old pal assume the new post.
"I'm happy for Conan," Will, 41, continued. "Getting to make appearances on his show over the years and kind of grow comedically with him has been one of the highlights of anything I got to do, so to get to be on the first 'Tonight Show' with him is super cool."
As for what Will has in store for his visit this evening, the star said the two will see how it goes.
"Nothing [is] set yet," he claimed. "We'll figure it out."