Green Day frontman Billie Joe Armstrong sang the classic "Wake Me Up When September Ends" at the "One World: Together At Home" event, leaving the curator Lady Gaga in tears yesterday, April 18.

Seated in his room with only guitar accompaniment, Armstrong performed their 2005 hit from their seventh studio album, "American Idiot." The 48-year-old punk rock icon delivered a subtly powerful performance, made more moving by the interspersed images of empty streets from otherwise busy cities.

A video from the Gaga Daily twitter account shows the Mother Monster emotional over the song. "Thank you so much to Billie Joe and Green Day for this beautiful song," Gaga said before turning to Armstrong's on-screen performance. "I know how much you love the world, I've always known since I was a kid."

pic.twitter.com/1YqWe70FbF Lady Gaga is crying during Billie Joe Armstrong's performance of "Wake Me Up When September Ends"... and so are we #TogetherAtHome

— Gaga Daily (@gagadaily) April 19, 2020

Fans have sent their support to both Gaga and Armstrong, expressing how they also cried over the performance. Others are now looking for a project between the two artists, with one fan writing that he's "officially waiting for a Gaga X Green Day collab now."

#ThankYouLadyGaga @GreenDay @ladygaga you're not alone in feeling this way. I cried the whole time. It was so emotional and Billie Joe's words are always so moving, profound and poetic. I'm so glad you got him to do this. Thank you to you both. #TogetherAtHome April 19, 2020

"When September Ends" and No Fun Mondays

"Wake Me Up When September Ends" had become the anthem for loss and grief. Armstrong originally wrote it about his father who died from esophageal cancer when he was ten years old. Aside from becoming a hit upon release, the song has also been used as a dedication to victims of Hurricane Katrina and the September 11 attacks.

Billie Joe Armstrong has also appeared in the Fox - iHeartMedia collaborative fundraiser, the "iHeart Living Room Concert for America," hosted by Sir Elton John. The earlier at-home concert raised funds for food banks as well as for first responders. Among the other artists present in the event were Alicia Keys, the Backstreet Boys, and Dave Grohl.

Also, to keep fans occupied in the middle of the quarantine period, the Green Day frontman has launched his YouTube series, "No Fun Mondays," where he covers a song each week "until we're let back out into the world." He first covered "I Think We're Alone Now" by Tommy James and the Shondells before officially launching the series with Johnny Thunders' "You Can't Put Your Arms Around a Memory."

Armstrong has also featured The Bangles' Susanna Hoffs in their rendition of the hit "Manic Mondays." As his Easter treat, Armstrong released his version of the 1983 Avengers' single "Corpus Christi."

One World: Together At Home

The World Health Organization, together with Global Citizen, hosted the "One World: Together At Home" concert, curated by Lady Gaga and featured performances from Niall Horan, Adam Lambert, Jennifer Hudson, Kesha, Jessie J, Common, Billy Ray Cyrus, Camila Cabello, and Shawn Mendez, and Lizzo.

It also featured appearances from celebrities John Legend and Chrissy Teigen, Matthew McConaughey, Samuel L. Jackson, Ellen DeGeneres. The live-streamed event also featured medical experts and different front liners to raise awareness about the pandemic better.

True to its "One World" vision, the online concert also included performances from artists hailing from different parts of the world. Among them are Hussain Al Jassmi from UAE, Lisa Mishra from India, Jessie Reyez from Canada, Angèle from France, and Sebastián Yatra from Colombia.