Daniel Ricciardo will no longer drive for Red Bull on Wednesday afternoon following tweaks to his test programme.
The Australian was initially set to sample the Pirelli tyres at Silverstone on the first afternoon, but he will now step into the RB9 on Thursday afternoon.
The change also means his run in Toro Rosso's STR9, which was due to take place on Thursday afternoon, has been moved.
"Hey guys bit of a change to my testing program this week," he tweeted. "Drive my Toro Rosso tomorrow morning and the Red Bull tomorrow afternoon."
Red Bull have confirmed that Mark Webber, who was due to test on Thursday afternoon, will not take part in the test.
Antonio Felix da Costa is testing on Wednesday while Carlos Sainz Jr and Sebastian Vettel are scheduled to drive on Friday afternoon.
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