American Idol champ Kris Allen canceled his Wednesday night appearance on The Tonight Show with Conan O'Brien because of his maternal grandmother's death.

Taking Allen's place on the late-night talker will be Idol pal Allison Iraheta, performing "Barracuda."

"I know I was supposed to do Conan ... but there was a death in my family," Allen said on Twitter. "But everyone watch [Allison]. She is filling in. And by filling in, I mean [she] is gonna rock Conan's face off."

Iraheta responded to Allen's messages by saying on Twitter, "Love ya man. Keep yo head up." (Follow TVGuide.com on Twitter for more breaking news and scoop.)

Allen, Iraheta and Season 8's other Top 12 finalists are currently on the road with the American Idols Live Tour. Allen's rep told Access Hollywood that he is not expected to miss any dates, and will return to the tour in time for the July 16 stop at the Staples Center in Los Angeles.

sorry to here about the death in Miss Allan Family your Family is in my Prayers at this time of need.

I hope his mom is doing all right as well. Death can be a difficult thing to deal with.

I heard about this a couple of days ago. My prayers are with Kris and his family.