Rocker Adam Lambert was front-and-center for ET on the Grammy red carpet Sunday night, and you may be surprised as to who made his first-ever best and worst-dressed list!

Katy Perry showed up wearing Zac Posen, and Adam says, "I really liked what she was doing; I thought it was a little different."

Taylor Swift wore a full-length, open-back KaufmanFranco dress, and Adam says, "She looked classy, sophisticated and elegant."

Fergie looked "Fergilicious" in Emilio Pucci, while Rihanna (in a cream-colored Elie Saab gown) came in at the last minute "like Cinderella getting to the ball -- she looked fantastic."

The "Glambert" Award went to none other than Lady Gaga, "because she lives on her own fashion planet."

So who topped Adam's list? Dressed in Tony Ward, P!nk! "She looked like a star -- she hasn't performed at the Grammys for 9 years, so she came back with a bang … she looked classy and she looked beautiful."

Of course, there has to be balance. Who was "a big fat fail"? Watch the video to see who landed on Adam's worst-dressed list…

The producers of ET want to thank Adam for rocking the red carpet with us.