Watch AGT's Thomas Day's Powerful Performance of Billie Eilish Song as He Returns to the Stage

"America's Got Talent" wildcard Thomas Day wows fans as he powerfully performs Billie Eilish hit song, "When the Party's Over." The 17-year-old returned to the competition with a stellar performance after recovering from COVID-19.

Judges and viewers of "America's Got Talent" weren't expecting to be blown away when 17-year-old Thomas Day climbed on stage during Tuesday's semifinals.

Dressed in a white turtle neck underneath a grey jacket and matching pants, Day held on to the microphone as he began belting out the tune to Billie Eilish's song, "When the Party's Over."

He started with a low tone but soon revealed the strength of his sonorous voice as the song progressed, leaving the judges enchanted. The video of the stellar performance, which was uploaded on the show's official YouTube channel, has already racked up 49,000 likes since its upload on September 8.

[Day] first made headlines in June when he performed a cover of "Break My Heart" by Finneas.

While Day's performance made rounds on the internet, it didn't entirely garner positive reception as some users labeled his appearance on the show as "unfair."

Fans may recall that after the teenager passed through the Judge Cuts, he dropped out of the competition in the quarterfinals after reportedly testing positive for COVID-19.

Due to his diagnosis, he was given a wildcard, which allowed him to return. However, some fans thought it was biased after a clip of Day explaining his reason for leaving the show surfaced online.

In the video, the young talent said that he left the show because he couldn't make it to the show because of football, leaving out his alleged COVID-19 diagnosis. Nevertheless, Day seized the opportunity and didn't fail to charm judges, Sofia Vergara, Howie Mandel, and Heidi Klum.

He first made headlines in June when he performed a cover of "Break My Heart" by Finneas, which received a standing ovation from Simon Cowell. Away from the show, the teenager keeps busy as a high school football player in Brentwood, Tennessee.

Alongside a talent for sports, Day performs covers for hit tracks on his Instagram page and has over 128,000 followers. He is also good friends with YouTube star Logan Paul.

Season 15 of "AGT" has been filled with spectacular talents, which include dancer Frenchie Baby, teenage group The Divas and Drummers of Compton, and 14-year-old singer Kelvin Dukes.

However, it was 10-year-old Roberta Battaglia that stood out with her flawless voice as she performed Lady Gaga and Bradley Cooper's song, "Shallow," which earned a Golden buzzer from Vergara.