The dancer, who has been romantically linked to Idol eliminee Pia Toscano, was spotted watching the Top 7 performances on Wednesday night with his father Corky.
At one point, host Ryan Seacrest approached him to ask if he had a favourite Idol contestant, to which Ballas said that he is supporting Casey Abrams, prompting Seacrest to joke that he gave a "curveball" answer.
Toscano was one of the eliminated season ten finalists who returned to the Idol stage this week for a group performance of 'So What?' by Pink. She was joined by Naima Adedapo, Karen Rodriguez, Thia Megia, Ashthon Jones and last week's departee Paul McDonald.
She is scheduled to perform on next week's Dancing with the Stars results show on Tuesday, with host Tom Bergeron revealing this week that she will be accompanied by Ballas. He is currently competing in the ABC competition with actress Chelsea Kane.
Toscano and Ballas sparked rumours of a romance when they were seen having dinner together following her elimination, although they have both remained coy about the speculation, insisting that they are just friends.
Following this week's Idol show, Ballas took to his Twitter account to say: "Ha ha thanks @RyanSeacrest for the shout out, and for putting me on the spot... ;) (sic)"
American Idol continues tonight at 8/7c on Fox with another elimination and performances by Katy Perry and David Cook.
More from American Idol:
> American Idol: We recap the Top 7 performances
> American Idol: Who should go home?