Actor-writer-director Eric Stoltz is directing an episode of Grey's Anatomy in Season Five, which he deemed a significant and very rewarding project.

Without giving away any details, he called it "a more massive undertaking" than, say, his previous directorial work on Boston Legal and Law & Order.

"It's the difference between driving a bus and riding a bike — and on that bus are 17 unbelievably talented people," he says.

"[Grey's Anatomy] is an embarrassment of riches. It's quite mad, in a delightful way."

Stoltz is not at liberty to divulge any spoilers on what his Grey's Anatomy episode entails, or when it Season Five it will air, but he says this:

"It is really wonderfully character-driven, featuring a lot of people falling in and out of love. I'm very happy with the way it's going."

Steve Marsi is the Managing Editor of TV Fanatic. Follow him on Google+ or email him here.