Unable to obtain a quality drive for 2001, Gené opted to sign with Williams as test driver. He drove three Grands Prix for the team as temporary substitute. The first of these was the 2003 Italian Grand Prix, where Ralf Schumacher was unable to race because of a concussion. Gené replaced his teammate well, collecting four points for a fifth-place finish, but Schumacher was back in the car for the next race in the USA. Following a back injury to Schumacher at the 2004 USGP, Gené drove in the French and British Grands Prix, but subsequently lost the race seat to Antônio Pizzonia and did not race again in F1.