LONDON – Ferrari will retain Felipe Massa next season in what is planned to be a stop-gap deal before the arrival of Sebastian Vettel in 2014.Sources inside Ferrari say they have signed a contract with Vettel, which is thought to be an option to join in 2014 depending on their results.The contract is likely to define a position Ferrari must occupy in the title race at a point in 2013. Ferrari have decided to keep Massa as Fernando Alonso’s team-mate until then.The Brazilian’s future had been in doubt during the summer after a shaky start to the year, but Ferrari were determined to retain him if he had a strong performance in the Japanese Grand Prix last weekend to confirm a revival in the second half of the season.Massa 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.The Brazilian 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.Vettel’s arrival at Ferrari has been sanctioned by Alonso, who has a say in the identity of his team-mate. The Spaniard vetoed the idea of Lewis Hamilton joining the team earlier this year.Should it transpire, the line-up would produce a mouth-watering partnership which would undoubtedly be the strongest in F1 - with potential for huge friction.Vettel and Red Bull have denied the German has any arrangements in place with Ferrari, and the team insist he is under contract until the end of 2014.