Celeb-watchers are abuzz about a new couple: Oscar nominee Michelle Williams, 31, and ‘How I Met Your Mother’ star Jason Segel have reportedly taken their friendship to the next level.

The two have been pals for years, but it seems things have recently gotten a lot cozier. “They are smitten and very serious,” a source told Us Weekly magazine, adding the actress hasn’t been this happy “in a long time.”

Williams, who has a young daughter from a previous relationship with the late Heath Ledger, recently picked up her third Academy Award nomination for playing screen icon Marilyn Monroe in ‘My Week with Marilyn.’

In addition to his sitcom work, the 32-year-old Segel co-wrote and starred in ‘The Muppets,’ and is largely credited with helping to reboot the beloved franchise.