Lasse Wellander, longtime guitarist for the disco supergroup ABBA, has died at 70 years old after a battle with cancer.

His family shared the news via Facebook late Monday, describing their “indescribable sadness” over the loss of the “amazing musician… wonderful husband, father, brother, uncle and grandfather.”

ABBA’s Agnetha Fältskog, Björn Ulvaeus, and Anni-Frid mourned their bandmate on Instagram, describing Wellander as “a dear friend, a fun guy and a superb guitarist.”

“The importance of his creative input in the recording studio as well as his rock solid guitar work on stage was immense,” the “Angeleyes” singers went on, noting Wellander’s “integral role in the ABBA story.”

Born in 1952 in southern Sweden, Wellander learned to play the accordion and recorder before The Beatles inspired him to pick up a guitar in 1963, per his website.

He was a member of the rock band “Nature” until he was recruited by ABBA’s Ulvaeus and Andersson in 1974. Wellander recorded eight albums with the group, playing lead on pop gems like “Knowing Me Knowing You,” “Slipping Through My Fingers” and “Eagle.” He was also a regular in ABBA’s touring act.

After the Eurovision winners split in the early ’80s, the guitarist embarked on a solo career. Post-millennium, he helped contribute to the band’s resurgence, working on the soundtrack for the Meryl Streep musicals “Mamma Mia! The Movie” (2008) and “Mamma Mia! Here We Go Again” (2018).

Wellander reunited with ABBA for the 2021 album “Voyage,” the group’s first record in 40 years.