Although Red Bull team owner Dietrich Mateschitz has hailed Daniel Ricciardo's "excellent" test, he has refused to rule out Jean-Eric Vergne.
The battle to replace Mark Webber at Red Bull Racing next season is heating up as time is running out for the candidates to impress.
Toro Rosso's Ricciardo has emerged as the early favourite after being called upon to test for Red Bull during the recent Young Driver Test.
However, the Aussie is by no means the only driver in the frame.
His team-mate Jean-Eric Vergne is also in the running while team boss Christian Horner has expressed his desire to sign Lotus' Kimi Raikkonen.
For now, though, Mateschitz appears to be leaning towards promoting one of the Toro Rosso youngsters.
"There is no decision yet, and it is still under discussion within the team," Mateschitz told Autosport. "It will be announced after Budapest.
"But Ricciardo did an excellent job at Silverstone, and [Jean-Eric] Vergne was very good."