Sunnyvale's Dalton Rapatonni (second from left) is among the "American Idol" Top 4. He joins (L-R) MacKenzie Bourg, Trent Harmon and La'Porsha Renae. They performed songs by Sia on Thursday night's show.

Sunnyvale's Dalton Rapatonni (second from left) is among the "American Idol" Top 4. He joins (L-R) MacKenzie Bourg, Trent Harmon and La'Porsha Renae. They performed songs by Sia on Thursday night's show.

Michael Becker/FOX

Sunnyvale's Dalton Rapattoni is one step closer to winning American Idol after the top four contestants were revealed Thursday night.

MacKenzie Bourg, Trent Harmon and La'Porsha Renae are the other three.

Last week, Rapattoni talked about the challenges that come with being diagnosed as bipolar and how music has helped him.

This week, he showed just how much with an emotional rendition of "Bird Set Free." The contestants sang songs from the catalog of Sia, who told Rapattoni that she was also bipolar during a coaching session.

The lyrics were especially poignant after last week's revelation: 

"I don't care if I sing off key
I find myself in my melodies
I sing for love, I sing for me
I shout it out like a bird set free."

"You're always pushing through your limitations," said judge Keith Urban. "It's so inspiring."

Said judge Harry Connick Jr.: "I think it's something you needed to do."

The other Idol hopefuls were equally affected, standing after the performance and rushing the stage to hug Rapattoni. His mother had tears streaming down her face during the performance. (Earlier, he had performed the Beach Boys' "God Only Knows.")

Expect more emotion when Rapattoni returns home to Sunnyvale for the show's annual trek to the hometowns of its final four.

The schedule on Saturday:

8:30 a.m. Villagers Beauty Salon, 2209 Gus Thomasson Road, Dallas

10 a.m. School of Rock performance at San Jacinto Plaza, 105 San Jacinto Plaza, Rockwall

4 p.m. Parade, starts at Sunnyvale High School and goes to Town Center Park, 356 E. Tripp Road, Sunnyvale

5 p.m. Concert at Town Center Park

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