Toro Rosso's 2012 driver lineup will not be known until the end of this season, according to team principal Franz Tost.
Current drivers Sebastien Buemi and Jaime Alguersuari have been put under pressure to perform this year in order to maintain their long-term prospects with the team, such has been the pace of Red Bull Junior driver Daniel Ricciardo in Friday practice sessions.
However, both men have raised their games in recent races with Alguersuari scoring points in the last three events, and Ricciardo has replaced Narain Karithikeyan at the Hispania squad.
Parent company Red Bull will now continue to assess the performances of all three drivers for the rest of the campaign before deciding who to place with Toro Rosso next year.
"What our driver pairing will be in 2012, I don't know yet," said Tost. "This will be decided by Red Bull at the end of the season."
Tost believes that reserve driver Ricciardo will only benefit from his new surroundings, even if it means battling for the final few positions in qualifying and racing.
"At the start of the season, Ricciardo was out for us on Friday mornings for 90 minutes to learn the different racetracks, how the team works, how to give technical feedback, how to work with the engineers, even how to conduct himself for marketing activities and press work," he added.
"Now he's been offered the chance to race, and I can see only advantages in this. Participating in FP1 is not the same as doing a complete race weekend, so he will be much better prepared for next year. And he can't drive for Toro Rosso because we have two race drivers who are doing a good job."