permanent test driver replacing Takuma Sato. At Minardi, Nicolas Kiesa was unable to keep his seat and was released. Jos Verstappen left Minardi as a result of sponsorship problems and an unwillingness to spend another year competing with other backmarkers in the non-competitive team. Gianmaria Bruni, who had performed a limited amount of testing in 2003, was signed to a full-time drive. Zsolt Baumgartner was confirmed as the second full-time driver after the Hungarian government provided sponsorship; Baumgartner had performed replacement duties at Jordan in 2003 after Ralph Firman suffered injuries from a crash in Hungary. Completing the all-new line-up, Bas Leinders and Tiago Monteiro were signed as test drivers for 2004. Leinders was signed from the ranks of the World Series by Nissan, while Monteiro was signed from the American Fittipaldi Champ Car team. Heinz-Harald Frentzen and Sauber mutually parted ways at the end of 2003. Frentzen then moved out of F1 and joined fellow ex-F1 drivers Mika Häkkinen and Jean Alesi in the DTM. Nick Heidfeld was also released by Sauber, and appeared to have no drive for 2004. However several successful test drives at Jordan landed him a seat there. Fisichella left Jordan after 2003 having signed a drive for Sauber. This meant that Heidfeld and Fisichella effectively swapped seats. Sauber's other new driver was Felipe Massa, who left his test position at Ferrari and returned to the team where he had raced in 2002. As Sauber used Ferrari engines in 2003, Massa took considerable knowledge of Ferrari components with him. Choosing not to extend Justin Wilson's contract, Jaguar signed Christian Klien to partner Mark Webber in the R5. Wilson turned down a test drive and departed Jaguar to join the Mi-Jack Conquest Racing team in Champ Car racing in America. Björn Wirdheim was signed as their Friday test driver. The other Friday test drivers are Franck Montagny, who was rewarded for a championship year in the World Series by Nissan with a permanent test drive at Renault, Ryan Briscoe, who joined Ricardo Zonta as a test driver at Toyota, and Pedro de la Rosa, who returned to F1 as a test driver for McLaren. Mid-season changes Giorgio Pantano was replaced by Timo Glock at the . Pantano left Jordan after the , with Glock replacing him again for the remainder of the season. After Ralf Schumacher was injured during the , Marc Gené replaced him at