Feb.16 (GMM) Toro Rosso's new drivers look set to be given longer than just a single season to prove they can step up to the senior Red Bull team.
Daniel Ricciardo and Jean-Eric Vergne have replaced the Faenza based team's 2011 lineup and are tipped as likely contenders to oust the Australian veteran Mark Webber at Red Bull Racing next year.
But Franz Tost, Toro Rosso's team principal, said a 2013 promotion for either Ricciardo or Vergne is unlikely.
"I have no idea. But I doubt it, as the level of Red Bull Racing is extremely high," he told F1's official website.
"So my guess is that they will have to wait a little more. So far Mark has not given any hint that he is thinking of retirement."
Tost said Red Bull will only be looking for a driver with the 'wow-effect' to replace Webber, so 2013 could be too soon for Australian Ricciardo, or the French rookie Vergne.
Mark has not given any hint that he is thinking of retirement
"In general I would say that this wow-effect is not so easily manageable in a first season," said the Austrian. "But it definitely has to be delivered in the second season.
"I don't have a problem when a driver has a good race and at the next race he has a shunt -- that's part of the game. Both drivers will have a 'crash period' but that is part of their development phase," he insisted.
"It was the same with Sebastian Vettel. But at some point they have to get their game together -- and the question is who will be better at doing that? Let's wait and see."