From GMM - UPDATED, see belowSergey Sirotkin has finally signed a real contract to race a Sauber Formula 1 car in 2014.Before the Russian teen's visit to Hinwil this week, Sirotkin's race seat was a mere ambition as part of the Russian rescue deal.But Austria's Osterreich newspaper reports that a real contract has been signed now.The report said the information was confirmed at Spa-Francorchamps on Thursday by Sauber team boss Monisha Kaltenborn.Germany's Der Spiegel also reported from Belgium: "Sauber has taken the 17-year-old Russian Sergey Sirotkin under contract."Kaltenborn said Sauber, currently fielding German Nico Hulkenberg and Mexican Esteban Gutierrez, is yet to decide who Sirotkin's teammate will be.Hulkenberg, linked with Felipe Massa's Ferrari seat, admitted he is talking to "some teams" about 2014.Asked if he has ruled out staying at Sauber in 2014, he told Speed Week: "I don't rule anybody out today."Sergey Sirotkin on Friday confirmed reports he has signed a real contract to drive for Sauber in 2014."I'm a Sauber driver in formula one for 2014! Thank you all for your congratulations," the 17-year-old wrote on the Russian social network Vkontakte on Friday.