Watch WWE SummerSlam 2021 for Free: How to Stream the Movie Online at 123Movies. . The biggest party of the Summer is not only back, but for the first time ever, will be taking place in an NFL arena at the Allegiant Stadium in Las Vegas. Witness "The Head of the Table" Roman Reigns take on John Cena for the WWE Universal Championship, Nikki A.S.H. facing off against Charlotte Flair & Rhea Ripley in a Triple Threat Match for the WWE Raw Women's Championship, and The All Mighty WWE Champion Bobby Lashley defending his title against the unstoppable Goldberg.