Who will be first to gain one million followers on Twitter?

Ashton Kutcher and CNN, two of the most popular users on the social networking site, are facing off this week to find out just that.

“Last one to 1 million followers is a rotten egg!” Ashton wrote on his Twitter account on Wednesday.

The former star of That 70s Show promised a Guitar Hero video game to his millionth follower.

Larry King, host of CNN’s Larry King Live, has posted a video to YouTube responding to the challenge.

“Are you kidding? Do you think you can take on an entire network?” Larry said jokingly. “You’re playing out of your field. CNN will bury you.”

“You come on my show, I’ll go on your … Twitter, or whatever it is you do.”

As of Wednesday afternoon, Ashton had 916,481 followers, while CNN’s Twitter feed was at 947,371