For the first time, David Cook wasn't able to rock steady.
The American Idol contestant was rushed to a Los Angeles hospital following Tuesday night's performance show after experiencing what were likely stress-related heart palpitations.
"He was feeling light-headed," a on-set source told E! News, adding that paramedics were called to check the singer's blood pressure during a commercial break just prior to his performance.
Despite his palpitations, Cook insisted he go on with his performance and only after his minute-and-a-half in the spotlight did he get proper treatment.
"He went on and afterward he went to the hospital to be checked out for high blood pressure and high anxiety."
After examining the young singer, who was suffering from an accelerated heart rate and a spike in blood pressure, a doctor gave him medication to bring his blood pressure down and Cook was discharged.
He's currently back at the L.A.-area hotel where he and his fellow contestants are staying this season. "He is fine and not at the hospital," another show insider said.
Producers wanted the 25-year-old Missouri bartender to head to the emergency room before the show, which starts taping at 5 p.m. PT, was over, but Cook wanted to stay until the end.
A Fox rep told E! News the network "does not comment on the personal lives of the show contestants."
However, show sources suggested that Cook's condition was caused in part by Idol-related pressure and also due to recent bad news he received regarding his brother, who is battling cancer.
"After the show, [Cook] was in the elevator and said he was going to go to the hospital. He said he had high blood pressure and wasn’t feeling well. Now he’s back at the hotel," Idol producer Nigel Lythgoe said in a text message to Ryan Seacrest, who relayed the message on his radio show Wednesday.
For his part, Seacrest told listeners of his KIIS-FM broadcast, "I don't know what he was stressed about. He said yesterday that his blood pressure was high and he wanted to get checked out after the show."
Earlier in the evening, Cook chose to go contemporary at a time when others might have opted for classic, in this case taking on Dolly Parton's folksy "Little Sparrow," from her 2001 bluegrass album of the same name. The country star herself will perform on Wednesday's elimination show.
Meanwhile, Seacrest suffered an injury of his own just prior to the performance show, smacking his leg against the metal railings dividing the audience from the main floor while making a mad dash across the set.
"I thought, 'Oh, that's gonna leave a mark,' " he said on air Wednesday morning, adding that he soldiered on with his hosting duties after the application of several ice packs.