The Lizzie McGuire Movie

At her junior high graduation Lizzie McGuire (Hilary Duff) is forced to make a speech in place of the class president, Margaret Chan, where she trips over the backdrop onstage, bringing down the curtain on everyone on stage. Subsequently, this footage was secretly sent in to "Good Morning America" by her younger brother, although it was made more popular internationally by CNN. She and her friends then leave on a class trip to Rome accompanied by her rude and strict new high school teacher Miss Ungermeyer (Alex Borstein) and her class enemy (and ex-best friend) Kate Sanders.After discovering she is sharing a room with Kate, Miss Ungermeyer takes them to the famous Trevi Fountain where Lizzie throws a coin into the water, for good luck after. Several minutes later, she meets the famous European pop star Paolo (Yani Gellman) who exclaims that Lizzie looks just like his partner-for-singing/ex-girlfriend Isabella. Paolo promises to be at the Trevi Fountain the next day, if Lizzie wishes to see him again. The next day, Lizzie pretends to be sick (the doctor believes that she is sick, because he had seen her embarrassing moment on stage on CNN, convinced that her nervous system collapsed under humiliation), and sneaks off to meet Paolo. She has gone off to a drive with Paolo, and agrees to present an award with Paolo as Isabella, to prevent Isabella from being sued (Paolo supposedly writes all the music, and Isabella lip-synchs). Later, Lizzie discovers that she also has to lip-synch "What Dreams Are Made Of", but agrees to do that too. Kate finds out the truth but helps Lizzie instead of betraying her.Lizzie continues to pretend to be sick while making the dress she is going to wear for the show. Just when her scheme is about to be discovered, Gordo sacrifices himself, tells Miss Ungermeyer that Gordo was the one sneaking out, and gets kicked off the trip. Just as he's about to board the plane home, he sees the real Isabella (Hilary Duff) at the airport and discovers the truth about Paolo. Gordo and Isabella race to the music event to stop Paolo from making a fool of Lizzie on stage. Paolo's plan was to show the world that Isabella could not sing; ironically, it turns out that Paolo was the bad singer and lip-synched while performing. Isabella and Gordo pull the plug on Paolo's mic, exposing him, and Lizzie ends up singing "What Dreams are Made of" (the "theme song" of the film) in front of the huge audience inside the Coliseum with her parents and Matt (who came to Rome because the mom and dad missed Lizzie).Later at the hotel, Paolo's now ex-bodyguard Sergei has formed a new relationship with the high school principal, Ms. Ungermeyer. Ms. Ungermeyer is informed the truth about sneaking off from Lizzie, and Gordo earns her respect as a loyal friend to Lizzie. Lizzie and Gordo sneak away for the last time from the after party to go up to the roof to talk. Gordo reassures Lizzie that things will be just as good when they go back home and that he always believed in her. Then, Lizzie kisses him and thanks him. Then, both of them return to the after party because they cannot afford getting into more trouble as we see fireworks spell out the words "The End".Source: Wikipedia, The Lizzie McGuire Movie

Question: Who pretends to be Isabella in the movie?
Answer: Lizzie McGuire