Michael Keaton, one of the most beloved actors to ever wear the Batsuit, is all in on Batfleck.

The Batman and Batman Returns star was cornered by the lovely, privacy-respecting folks at TMZ about his thoughts on Ben Affleck's recent casting as the Caped Crusader in the Man of Steel sequel. The cornered Keaton gave a straightforward answer: "He's going to be great. He's going to be great."

Meanwhile, Affleck's Runner Runner co-star Justin Timberlake is also coming out in support of the new Batman casting. He told Fresh 102.7, "I think he's a brilliant filmmaker. I think he's an extreme talent so he could surprise a lot of people."

Beyond that, Timberlake also has a role he wants to play in the Batman movies: "The Riddler is my favorite villain. He was proper crazy. So if I'm gonna play crazy, I wanna play proper crazy."

For Keaton's part, he's not closed off to appearing in another Batman movie somewhere down the line.

"I could do anything," he said when asked about returning to the Batman series. "I could do anything."

Affleck makes his Batman debut in Warner Bros. and director Zack Snyder's Man of Steel sequel, scheduled to hit theaters on July 17, 2015.