Plastic Pucker! Christina's Lips Are 'Swollen,’ Top Docs Claim

Christina Aguilera sung her heart out in a comeback performance during the Whitney Houston tribute at the American Music Awards on Sunday night. But rather than gush over her pipes, fans couldn't stop talking about her massive lips! Click through seven shocking photos as three of the nations's leading plastic surgeons reveal to RadarOnline.com exclusively why the "Fighter" singer has gone too far!

"Christina's lips look like they've been enhanced, possibly within the last couple weeks, with a filler like Juvederm," America's Holistic Plastic Surgeon Anthony Youn, M.D., F.A.C.S. told RadarOnline.com.

"To me they look a little swollen, it could be that they've been a slight bit over-plumped," added Dr. Youn, who has not treated Aguilera.

NYC Triple Board Certified plastic surgeon, Adam Schaffner, MD, FACS agreed with his colleague. Although he has also not treated Aguilera, he said, "It appears her lips are larger, possibly due to injection with filler such as Restylane or Juvederm."

According to Benjamin C. Stong, M.D. www.kalos-plasticsurgery.com, "Christina's lips look much fuller and more voluminous at her AMA performance compared to earlier photos. Her upper lip looks particularly fuller. She appears to have decreased movement in her lips which is common following injections with fillers like Juvederm or Restylane which can briefly make lips less flexible until the swelling resolves and the material integrates with the tissues in the lips."

"You can particularly tell when she tries to purse her lips while singing. Fortunately, this is only a temporary effect and didn't affect her overall performance," added Dr. Stong, who has also not worked on Aguilera.