December Avenue and Regine Velasquez-Alcasid just shared the ASAP stage and blew everyone's minds.

On Sunday (06/09), December Avenue returned to the noontime variety show to perform the opening number of ASAP Natin 'To for the first time with Asia's Songbird. Together, they played crowd favorites 'Kung 'Di Rin Lang Ikaw' and 'Sa Dulo ng Walang Hanggan.'

I’m so happy I get to sing with you guys sobrang ganda ng mga songs nyo!!!!!! Thank you it was such a pleasure singing with😊

— regine alcasid (@reginevalcasid) June 9, 2019

In a tweet, vocalist Zel Bautista revealed that while writing what would be December Avenue's massive hit 'Kung 'Di Rin Lang Ikaw,' he was thinking of Ogie Alcasid's ballad 'Bakit Ngayon Ka Lang.'

Iniisip ko yung "Bakit Ngayon Ka Lang" habang sinusulat ko yung "Kung 'Di Rin Lang Ikaw".

Maraming salamat Sir @ogiealcasid isa kang inspirasyon at haligi ng OPM. 🙏🏼 pic.twitter.com/mGJE4bD46h

— Zel Bautista (@zelbautista) June 9, 2019

Bautista also thanks Velasquez-Alcasid on Twitter, writing, "It's an honor po!"

Grabe yun. Marami pong salamat, it's an honor po! @reginevalcasid 🙌🏻

— Zel Bautista (@zelbautista) June 9, 2019

Velasquez-Alcasid is currently a judge on ABS-CBN's Idol Philippines with Moira Dela Torre, James Reid, and Vice Ganda.

December Avenue are slated to embark on their first US tour this September to October, following their debut Canada tour that kicks off in July.

Watch their performance below.