Fernando Alonso and Sebastian Vettel could "easily co-exist together" as team mates, Ferrari principal Stefano Domenicali has said in a comment likely to send the Formula 1 rumour mill into overdrive.Media reports in May 2012 suggested Red Bull's double champion Vettel had signed a pre-contract agreement with Ferrari with a move likely in 2014.Alonso, also a double world champion, has a contract with Ferrari until the end of 2016 and is very much the number one in the current line-up with under-performing Felipe Massa.Ferrari's official website published an interview of Domenicali and Formula 1 chief executive Bernie Ecclestone who were both asked to comment on Vettel.Presented with a photo-montage of Vettel as he might look in Ferrari overalls, Domenicali smiled and said: "In life one should never say never.""I think they are both intelligent guys and they could easily co-exist together," he added.'END YOUR CAREER AT FERRARI'Alonso had a difficult time at McLaren when paired with Britain's Lewis Hamilton, who ended his extraordinary debut 2007 season level with the former Renault driver on points but ahead in the standings as runner-up.Alonso had eclipsed previous team mates and none of his subsequent partners have troubled him. Massa has not been on the podium since 2010 and is out of contract at the end of the 2012 season.Ecclestone said he would not advise Vettel to move but recognised it was a possibility: "Usually, a driver ends his career at Ferrari, therefore it could happen one day." "That wouldn't be a problem: both are drivers who are always looking for a new challenge and to be in the same team would be a new and big challenge. They would both think they can bear the other one, as they are sure of themselves and Stefano would do what was required to so that they were treated equally."It would be a case of doing what I did at Brabham in 1979 with Niki Lauda and Nelson Piquet. I told them, 'guys it's simple: whichever one of you is quickest is the team number one'," said Ecclestone.