American Idol fans, start preparing those goodbye tributes: Simon Cowell announced today that this year’s ninth season will be his last. The irascible judge told the nation’s TV critics in Pasadena, CA that he will team with Fox to launch a stateside version of his popular UK show The X Factor in fall 2011. “We did talk about me staying on both shows but when we looked at the practicalities of that, it was impossible,” Cowell told the press. “In my opinion, it’s like having a good player and a good football team. The two have to be okay together. I believe it’s not my show, but it’s still very close to me. We made sure when we did this, that I would be protected. I’m confident it will continue to be the No. 1 show. Everyone is committed to keeping it that way.”

Like Idol, X Factor is a televised talent search that pits contestants against one another and the prize is usually a recording contract. The UK version was responsible for the launch of Leona Lewis, among others. The show divides contestants into four categories — guys, girls, groups, and singers of all ages — and already airs in many countries. “It’s a big, big production,” said Cowell, who literally signed his contract with Fox at the press conference today. “There is no upper age limit on X Factor and groups are allowed to enter. We gave ourselves time to set it up. It gives us time to work out who the judging panel will be.

“I’m doing X Factor in America because I believe I can find someone incredibly talented through this process,” Cowell continued. “This country, thank God, has got thousands and thousands of people still waiting to be discovered. I want to find a star at the end, I genuinely do.”

Cowell said he was offered more money to stay on Idol but it wasn’t about the cash. “I felt like doing something different,” he said. “I want to leave Idol this year bigger and better than it’s ever been before. Having already done the auditions, it feels fresh, it feels relevant. I like the contestants this year. This final year for me feels different. I never would have wanted to walk out when the show was No. 21 in the ratings. You want to leave on a high. It’s been a fantastic time. We’re going to do something new. America needs a different type of show.”

As for Cowell’s replacement, the Fox suits said they have plenty of time to figure out how to make up for the huge void. “We are not going to find a Simon clone to do what he does because he is one of a kind,” said Peter Rice, Fox entertainment chairman. “The reason we are making the announcement in January is to give ourselves time and allow people to come forward. We were frankly surprised at the enthusiasm in replacing Paula. We have to make sure the chemistry is as good as it can be. So I don’t think we will rush into that.” As for Ellen DeGeneres’ quip to EW recently about her threatening to bolt if Cowell leaves, Rice deadpanned, “I think she was making a joke.”

Speaking of Abdul, Cowell did have some promising news about the ex-Idol judge: “I adore Paula. Whatever happens, I will be working with her in some capacity because I miss her. You’re gonna have to watch this space!”