Serena Williams delighted fans by joining a mosh pit at Green Day's concert at SoFi Stadium in Los Angeles on September 14, showcasing her enthusiasm for the band. Dressed in black, Williams was seen joyfully running in circles with fellow concert-goers, a moment captured in viral social media clips. After the show, Billie Joe Armstrong thanked fans in an Instagram post, to which Williams commented, expressing her admiration for him. This isn't her first time attending a Green Day concert; she has long been a fan, previously sharing her love for the band on social media and participating in fan challenges. The concert was part of Green Day's 'Saviors' tour, which celebrates the 20th anniversary of their iconic album 'American Idiot'. Williams, now retired from tennis, appears to be fully embracing life as a fan, enjoying moments like these alongside her supporters.