Katherine Heigl filming "Knocked Up"

"Grey's Anatomy" babe Katherine Heigl will be heading straight into shooting the big-screen comedy "Knocked Up" as soon as ABC's megahit reaches its quickly approaching season finale. "It's with Judd Apatow, who did 'The 40-Year-Old Virgin.' I'm the knocked-up one," says Heigl with a laugh. "It's crazy because I have to wear like a big prosthetic belly the whole movie. I'm of age to be having children, but it's just a weird concept to me." The actress, who plays Isobel "Izzie" Stevens on the hit ABC series, admits, "It's a little rough going directly from the show to another project. I wouldn't have minded a little vacation. As grateful as I am to be on the show and as wonderful as it is, at this point, nine months in, I think we're all a little burnt out and tired, and we need some new scenery for a few months. I'm sure we'll be champing at the bit to come back." And what can we expect in "Grey's" upcoming episodes? "There are some big changes, and I'm excited as an actor to play all of this stuff that they are beginning for me, but it's also hard to watch my character go through what she's going through. I don't want to give you more than that or they'll kill me," says Heigl. In the meantime, she's just enjoying the ride. "My career seems to have finally gotten to where I don't have to worry about it so much. It's not as much of a struggle, so I can enjoy it more and relax into what it's become." [Cleveland]