Sutil casts doubt on Sauber's future SAO PAULO (Reuters) - Unhappy German driver Adrian Sutil cast doubt on Sauber's Formula One future on Thursday, a day after the Swiss team threw his career into question by announcing a new lineup for 2015. "There are certain things to talk about, definitely," he told reporters at the Brazilian Grand Prix. "I mean, they have confirmed two drivers but it doesn't mean the drivers are going to drive and it doesn't mean the team is going to drive," added Sutil, whose own contract was also understood to cover next year. So there's no real change from last weekend to this weekend. It's just an announcement and now of course in my situation I think I have to do some talking to sort out things. Sauber have confirmed Sweden's Marcus Ericsson and Brazilian Felipe Nasr for 2015, both drivers with substantial financial backing, in place of Sutil and Mexican Esteban Gutierrez. After Caterham and Marussia went into administration, missing the U.S. Grand Prix and Brazilian race, the focus has been on Sauber, Force India and Lotus as other privately-owned teams facing a financial squeeze. Sutil, who joined the Sauber team this season, did not deny he had originally agreed a two-year contract but said Formula One was a "different business' now. "I am not frustrated but that's just how it is in Formula One since many years," he said. There was speculation in the Interlagos paddock that lawyers might become involved. Sauber principal Monisha Kaltenborn, who has a masters degree in international business law from the London School of Economics and once ran Sauber's legal department, told reporters that the situation would be dealt with internally. We've announced our two drivers. I am not aware that next year more than two cars would be used," she said, making the point repeatedly and firmly as reporters persisted. We've announced our drivers and that's how it's going to be. If there are any other points related to it, these are internal matters which we will discuss internally. Asked about Sutil's comments regarding the team's future, Kaltenborn replied: "What I have to say to him, I will also tell him first. "I don't know why he said that," she added. You'll have to ask him that. The views I have on it I will tell him. Kaltenborn confirmed that a plan to bring Russian teenager Sergey Sirotkin into Formula One had foundered. "I don't expect that to go on next year," she said. The Mexican sponsors who have been at the team with Gutierrez are also expected to leave. "Since we don't have Esteban on board, it is not there," Kaltenborn said of that backing. Sauber have already announced that Banco do Brasil is coming in with Nasr while Ericsson brings other backers and Kaltenborn recognized that was an important part of both signings. You have to look at the overall situation in Formula One. It's very challenging, and when private teams make decisions they have to take financial aspects into consideration," she said. That's the situation, and it's no different for us. Reporting by Alan Baldwin, editing by Ken Ferris