Donald Trump by Trae Patton/NBC Photo Donald Trump by Trae Patton/NBC Photo

What's it like to tell Gene Simmons to KISS off? To tell Marilu Henner to grab the next taxi? Such questions Donald Trump could face once The Celebrity Apprentice debuts Jan. 3. "In some cases in particular, I had a hard time firing some of these people," Trump told reporters during a Monday conference call, "because I've known them, not necessarily personally, but I've known their achievements. Possibly firing Olympic gold medalists... people that I've watched... is certainly not an easy thing."

Trump also teased tensions among the celeb cast, which includes the likes of Stephen Baldwin, Lennox Lewis and Vincent Pastore. "There's some unbelievable hatred among the [players], beyond anything in Apprentice 1 or 2. You wouldn't believe it."