BBC Formula 1 correspondent and lead commentator for BBC Radio 5 live, James Allen, explains what is going on at Sauber, who have failed to overturn a court ruling that asserts that Giedo van der Garde must race for the team at Sunday's Australian Grand Prix.

Van der Garde, 29, a former test driver for Sauber, says he was promised a race seat for this season, a claim backed by the Victoria Supreme Court this week.

Marcus Ericsson and Felipe Nasr are the team's nominated drivers for 2015.

Australian Grand Prix coverage details.

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