A visibly upset Mark Webber claimed that his Red Bull team are backing Sebastian Vettel ahead of him, and that he is seen to be "inconvenient". The Australian has led the world championship for much of the season and goes into the penultimate round here, Sunday's Brazilian grand prix, 14 points ahead of Vettel.

Webber said: "I think I wasn't supposed to be in the hunt at all, so it's been maybe quite inconvenient, but I've enjoyed every minute of it."

Asked if Red Bull were emotionally behind his German team-mate, Webber said: "Fucking obvious, isn't it? Of course. When young, new charges come on to the block that's where the emotion is. That's the way it is. That is absolutely fine because I have had a great opportunity with a great car to do some great things this year. I've got favourites in life. Favourite people I like to be with. That is human nature."

Asked if Vettel should support him in Sunday's race, he replied: "If it hasn't happened by now, it's never going to happen. Nothing has changed between Seb and I over the last five or six races. The only thing different is that Fernando [Alonso, of Ferrari] is leading [the drivers' championship]. We're in different parts of our career as well so it's not as easy as some people might imagine. Obviously Seb has never led this year and I have. We'll see on the Monday after Abu Dhabi if we have taken the right approach."

Christian Horner, Red Bull's team principal, has gone out of his way to stress that the team have been even-handed but the suspicion lingers that Vettel is the favourite. He is the protege of Helmut Marko, the Austrian Red Bull consultant. He is 23 and German, whereas the Australian Webber is an old sweat of 34. Even though he is contracted for next season there must be serious doubts about Webber driving for the Milton Keynes team again – especially if he goes on to win this year's title; he is 11 points behind Alonso.

In May Red Bull launched an inquest into what Webber described as a "fucking disaster" after their drivers crashed into each other. In July there was more controversy at Silverstone, when Webber had to hand his upgraded front wing to Vettel before qualifying.

While Vettel led his team-mate in the drivers' championship there was some justification for Red Bull's approach. But Webber went ahead after Vettel suffered a number of mishaps, betrayed by both his car and his impetuous driving.

Red Bull have taken 14 pole positions in 17 rounds this season. But they have converted that into only seven wins (four to Webber) and now Alonso's Ferrari is the favourite to lift this year's title. The fact that Red Bull will not ask Vettel to support Webber on Sunday increases Alonso's chances, given the risk of the Red Bulls clashing again.

Webber said: "I'm a driver, and I think that of course you increase your risk of that happening if you race each other and potentially take each other out, or race as hard as you want all the way to the end then you might not get certain championships. But it's certainly not my decision and what I think is not really all that important to how we will probably go about it. You'd need to ask the people who run the team."

According to Alonso, Felipe Massa, the flop of the Formula One season with no wins and only five podium positions, is the key to Ferrari lifting this year's championship. The Spaniard said: "Felipe is normally very strong here. I think the best thing for us, for me in the championship, for the numbers, is to have Felipe winning the race because he takes 25 points from everybody else."

Massa has twice won his home grand prix and has taken pole on his last three attempts.