Ferrari will retain Felipe Massa next season in what is planned to be a stop-gap deal before the arrival of Sebastian Vettel.
Ferrari sources say they already have a deal in place with double world champion Vettel, with an option for the 25-year-old to join them in 2014.
But Red Bull team boss Christian Horner insists Vettel will not leave.
He told BBC Sport: "Sebastian Vettel, without a shadow of doubt, will be part of the Red Bull Racing team in 2014."
Vettel's potential move to Ferrari has been sanctioned by Fernando Alonso, their number one driver.
The Spaniard, himself a double world champion, has a say in the identity of his team-mate and vetoed the idea of 2008 world champion Lewis Hamilton joining Ferrari earlier this year.
Alonso, 31, won the world title in 2005 and 2006 with Renault but has not finished higher than second with Ferrari. He currently trails Vettel in the world championship by six points.
Should Vettel move to Ferrari, the team's line-up would undoubtedly be the strongest in F1 - but with potential for friction. It is notoriously hard for teams to accommodate two drivers with championship aspirations.
Vettel and Red Bull have both denied the driver has any arrangements in place with Ferrari. Red Bull insist the 25-year-old, who won the title in 2010 and 2011, is under contract until the end of 2014.
However, Red Bull adviser Dr Helmut Marko - the right-hand man of company boss Dietrich Mateschitz - has already said the contract contains performance clauses and Red Bull could not make Vettel stay if he wanted to leave.
Hamilton has recently signed a three-year deal to join Mercedes, Alonso is under contract to Ferrari until the end of 2016, while Jenson Button is under contract to McLaren until the end of 2014.
Massa's future had been in doubt during the summer after a shaky start to the year, but Ferrari were determined to retain him as long as he finished the season strongly.
The Brazilian, 31, followed up a second-place finish in Japan - his first podium for two years - with another strong race in Korea at the weekend, qualifying sixth and finishing fourth - 6.2 seconds behind Alonso.
Vettel's team-mate, Mark Webber, is on a one-year deal until the end of 2013 and could well retire at the end of next season ahead of the introduction of new chassis and engine regulations in 2014.
Massa is expected to be confirmed in the Ferrari seat for 2013, his eighth consecutive season with the team, in a matter of days.
Team boss Stefano Domenicali said of Massa after the Korean race on Sunday: "Very good, I'm very happy.
"He did an excellent race and an excellent qualifying. But I have to say he's [been] doing an excellent job since a couple of races, so this is really very promising for the end of the season.
"And if I want to anticipate the next question that I'm sure someone will ask, very soon you will know what will be our position in that respect.
"For sure, he's understanding now better the car, he's understanding better the tyres. We believe that he's a very, very strong driver, there's no doubt. Otherwise we would already have taken a different decision."
Ferrari president Luca Cordero di Montezemolo said he wanted to avoid a problem with rivalries, regardless of who was driving: "2014 is still to come but I don't want to have two roosters in the same henhouse, rather two drivers who race for Ferrari and not for themselves.
"I don't want problems and rivalries, which we didn't have between Schumacher and Irvine, between Schumacher and Barrichello, between Alonso and Massa or Massa and Schumi or Massa and Raikkonen."