When ECW closed in 2001, Van Dam signed a contract with the World Wrestling Federation (WWF, now WWE) and was involved in the Invasion storyline, where several former WCW and ECW wrestlers joined forces against WWF wrestlers. After the Invasion ended, Van Dam wrestled the following years as singles and tag team wrestler, winning the Hardcore, Intercontinental, European, Tag Team and World Tag Team Championships. At WrestleMania 22, Rob Van Dam won the Money in the Bank ladder match. After this victory, he challenged WWE Champion John Cena to a title match at One Night Stand, an ECW-themed PPV. At the event, Van Dam defeated Cena and won his first world championship. Two days later, Paul Heyman awarded Van Dam with the reactivated ECW World Heavyweight Championship making him the only man to hold both titles at the same time.