Lance Bass told Meredith Vieira on Thursday, Sept. 10, that his former 'N Sync bandmate Justin Timberlake has "completely changed" since the birth of his son, Silas. Credit: Jason Merritt/FilmMagic

This dad is different! Lance Bass opened up to Meredith Vieira on Thursday, Sept. 10, about how first-time fatherhood has completely transformed his former 'N Sync bandmate Justin Timberlake.

Bass ran into Timberlake, 34, on Wednesday inside 30 Rock, where Jessica Biel's husband was shooting his epic appearance on The Tonight Show with Jimmy Fallon. "Well, I have to come all the way to NBC just to see my friends. Justin was in the building — he was shooting Fallon or Seth Meyers," Bass dished.

A photo from the random run-in was posted to Bass' Instagram account. "Well well, look who's in the #NBC house today!" he wrote, alongside a snap of himself with JT. "@JustinTimberlake and Cousin Rachel! Catch JT on @jimmyfallon !"

Well well, look who's in the #NBC house today! @JustinTimberlake and Cousin Rachel! Catch JT on @jimmyfallon !

A photo posted by Lance Bass (@lancebass) on Sep 9, 2015 at 10:03am PDT

Bass, 36, noted to Vieira that it was his first time seeing Timberlake since the "Mirrors" crooner welcomed his son with Biel this past April.

"It’s been five months and it’s so amazing to see a friend go through this, because you know, I grew up with him since he was 14 years old," the SiriusXM radio host recalled of their days as '90s and millennial heartthrobs. "But to see this amazing dad now... all he wants to talk about is the kid."

Indeed, on Wednesday night's episode of The Tonight Show, proud papa Timberlake brought along some baby photos of his 5-month-old son to share with Fallon and the audience.

"[He's] completely changed and you have to," Bass said of Timberlake. "I mean I can’t wait to be a dad myself just because I would love to know what that selflessness feels like."

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Bass shared that he and his husband, Michael Turchin, have a game plan for parenthood.

"One of the reasons I wanted to marry him was because I want to start a family, and we definitely in the next two or three years want to start that family," he dished. "I know people are very on the fence with IVF and all this stuff, but people have been doing it for years. With us, of course we want to find a surrogate to have our own kids, but now I was just reading with stem cell research and all this, and that’s of course up to the minute, now they are saying with the skin cells of a male you can actually produce an egg and fertilize [it], so you can have biological kids with two males."

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