In , after the CART season ended, Mansell returned to F1 and re-joined the Williams team. Since he had left it in 1993, the team had undergone some significant changes. Damon Hill had been promoted from test driver and was running full-time in one car. Prost, Mansell's replacement, won the 1993 Drivers' Championship and then retired after the season. This allowed Williams and Ayrton Senna to finally work out an agreement, and the team received a new sponsor in Rothmans International for a season in which they were expected to remain as champions. However, the car proved unreliable and tricky to handle early in the season, leading Senna to retire from the opening rounds despite claiming pole. In the third race at Imola, Senna was killed in a crash on the Tamburello curve.