Daniel Ricciardo joins Red Bull for Silverstone F1 test

The Australian, who will also appear for Toro Rosso on Thursday afternoon, is a leading contender to take Mark Webber's race seat next year.

Ricciardo's test, which is possible because of the restrictions on race drivers being lifted to allow teams to try the new Pirelli rubber that will be introduced in next week's Hungarian Grand Prix, will allow the team to evaluate his suitability for the drive.

He is known to be highly-rated by the crew that ran him for Red Bull in the young driver tests in 2009 and 2010 and a strong performance at Silverstone could be decisive in whether he lands a race seat for next year.

JUNIORS HAVE TO BE 'RIGHT MATERIAL'

Ricciardo's test confirms that he is considered the more realistic contender for the Red Bull seat of the two STR drivers.

When asked during the German GP weekend about whether he would like to see a Red Bull junior land the role, Ricciardo said he does but only on the proviso that either he or Jean-Eric Vergne are good enough.

"If we weren't pulling our weight then I wouldn't expect them to take us, I would expect a world championship team to pick a world championship driver," he said.

"Whatever decision they make, I'll understand it and it will be the best decision for the guys.

"Ideally we want to step in but if they choose someone else we obviously weren't the right material for them."

How Red Bull decides second seat

Kimi Raikkonen is also in the running for the seat, as is Ricciardo's team-mate Vergne, who will run for Toro Rosso at Silverstone on Friday morning.

Red Bull has confirmed that both Mark Webber and Sebastian Vettel will run in the test, on Thursday and Friday afternoon respectively.

They will share driving duties with Red Bull juniors Carlos Sainz Jr and Antonio Felix da Costa, who will also appear for STR along with a third junior driver, Daniil Kvyat.

Silverstone test line-up as announced by teams so far:

* The driving schedule will be confirmed each morning