Christian Horner says it's too early to judge whether Jean-Eric Vergne or Daniel Ricciardo are ready for a move to Red Bull.
The young duo have impressed for Toro Rosso, with Vergne in particular showing strong recent form by netting points in Monaco and securing sixth place in Canada last weekend - the best result of his fledgling Formula 1 career.
But Red Bull boss Christian Horner says it's too soon to tell if either Vergne or Ricciardo are Red Bull material, should the team elect not to retain Mark Webber next season.
"He [Vergne] had a very strong weekend. He drove a good qualifying and a strong race so he deserves it," said Horner.
"I think the two of them are both very capable drivers and they are feeding off each other. They almost alternate over different weekends, and it is great to see young talent starting to flourish."
When asked if he felt either man was ready to step up to a team like Red Bull, Horner replied: "It is still too early to make a call on that, but we have all the information through working with those guys and following them closely.
"But it is great to see the progress they are making."
No concrete decision has yet been made on Webber's future. That will most likely come during the summer break.