Park, a 21-year-old college student from Northbrook, IL, was the first semifinalist to learn his American Idol fate. He had sung John Mayer's "Gravity" during Tuesday night's male performance show. However the judges had been largely apathetic, with Randy Jackson saying he hadn't seen "anything special" and the performance had been "kind of flat" and Ellen DeGeneres adding that Park needed to "feel the song" more.
Simon Cowell had even predicted Park might be eliminated on Thursday.
"I think [your a capella group] Purple Haze might get their lead singer back this week," Cowell said. "Because the problem is, there's nothing to get excited about that. It was what I call a 'So What?' performance."
"Meeting these guys and these girls, I've really enjoyed my time here," he said. "And working with the band and the crew, just everyone."
Sellers, a 27-year-old church singer from Joliet, IL, was the second semifinalist to see his American Idol journey end.
All four judges had panned Sellers' Tuesday night performance of Marvin Gaye's "What's Going On," with Kara DioGuardi criticizing him for "always doing too much," Jackson describing it as "so close but so far at the same time," and DeGeneres having to resort to complimenting his preference for one-piece pajamas to find something good to say.
The feedback had left Sellers so frustrated that he'd invited Cowell -- who had told him that "nobody can take you seriously as an artist" -- to come see him sing in church and asked the judges to just tell him what they wanted him to sing next week. However, similar to his Park about remark, Cowell had suggested Sellers wouldn't be getting a chance to sing anything the judges recommended.
"I'm not sure you're going to be here next week," he quipped.
After his elimination, Sellers told Seacrest that he didn't believe his outspokenness had contributed to his Idol exit.
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"No, I don't think my mouth got me in trouble," he said. "I leave here happy. I appreciate you all to the fullest, I really do. And most of all, everyone needs to go out and get a onenie."
Delamor, a 22-year-old corporate singer and sales associate from Miami, FL, was the first female semifinalist eliminated.
She had sung Creed's "With Arms Wide Open" to mixed reviews from Idol's judges during Wednesday night's female performance show.
Jackson had said Delamor "didn't do enough with it" and called it "flat," while DeGeneres had noted it there were "pitch problems and it had "almost worked but not quite."
But DioGuardi and Cowell had both been more positive, with DioGuardi calling it her "favorite performance of yours ever" and Cowell congratulating Delamor for doing her best to follow the judges' sometimes "contradictory advice."
"You took the point, which is you didn't choose a safe song, you attempted to make it your version, and then you kind of got 80% of it right," he explained.
However DioGuardi backtracked from her Wednesday night praise prior to Seacrest's announcement of Delamor's ouster.
"Michelle, I have to say, as moved as I was in the room [last night], when I went back [later] to watch it, it was technically off," she said. "I think I was wanting that connection with you -- that believability -- and I got that in the room, but it wasn't great, it really wasn't, and I think you may be in jeopardy."
Following her elimination, Delamor said she believed an excessive focus on the judges' feedback contributed to her Idol downfall.
"I think I was so wrapped up in trying to do everything right while being judged that I kind of lost sight of just performing," she said. "It's okay, I'm going to keep going and I know I was made to do this... thank you everyone, thank you so much."
Vaughn, a 16-year-old high school student from Fort Collins, CO, was the last semifinalist eliminated.
Similar to Sellers, all the judges had been critical of her performance of Miley Cyrus' "The Climb."
"You always want me to keep it real with you right? It didn't work for me, man. It was tough for me. It was excruciating!" Jackson said Wednesday night.
"I was going to say unfortunately the same thing as [Randy]. I did not feel you connected to the song," DeGeneres added.
"I think that there are a lot of people out there who really like you... and you're a really good performer. Unfortunately honey, you need about a year of really strengthening your instrument," DioGuardi said.
"Look, I agree, I don't want to make this any worse than it already is because it was, you know, a complete and utter mess. to be honest," Cowell said.
Both Vaughn and the judges appeared to have anticipated her elimination.
"It's very obvious who is going to go home tonight," Cowell told Seacrest before the Idol host revealed whether Vaughn or Lacey Brown would be the second female semifinalist ousted.
"Maybe to you," Seacrest quipped.
"To everyone watching," Cowell replied.
Vaughn appeared unfazed by her exit after it was announced.
"I think I can definitely use some more experience and I mean I'll do my best from here on out," Vaughn said as she laughed and smiled. "The experience was good."
One more semifinals round will determine American Idol's Top 12 ninth-season finalists.