Christian Horner has told Toro Rosso's new drivers not to expect automatic promotion to Red Bull when Mark Webber retires.
With Webber being tipped to hang up his helmet at the end of this season, the race is on to see who will replace in the Aussie in what is one of the most coveted race-seats on the grid.
Daniel Ricciardo is being tipped as the favourite after Red Bull advisor Helmut Marko said that the new Toro Rosso signing is "likely" to take his fellow Aussie's drive in 2013.
However, Red Bull team boss Horner has warned Ricciardo and his Toro Rosso team-mate Jean-Eric Vergne that driving for Red Bull's junior team does not make them the favourites.
"We are fortunate to have two guys as talented as Jean-Eric and Daniel that fully deserve their chance in the Toro Rosso and I am fascinated to see how they evolve," he said at the Autosport International show.
"There is nothing guaranteed to those guys, they have got the opportunity and it's now down to them to take it and develop. We will be able to see, compared with each other, how they are progressing."