Christian Klien will be allowed to act as Red Bull's third driver over the next three Grands Prix after motorsport chiefs changed their rules.
Klien was replaced by Vitantonio Liuzzi for the next three races but the rules prevented him from driving in practice.
But now Klien will be able to test on the Friday of San Marino, Spain and Monaco before possibly resuming racing.
The Austrian was previously ineligible because he had raced in more than six Grands Prix in the previous two years.
The sport's governing body the FIA said the rule was changed "following a unanimous request from the teams".
It added: "As a result, any driver with a Formula One super licence may now run as a third driver on Friday."
The rule was set up to give younger, less experienced drivers a chance driving under Grand Prix conditions.
Red Bull argued that other teams such as McLaren have used third drivers with far more F1 experience than the 22-year-old Klien.
"The current status was intended 'to prevent' older drivers filling spots 'instead of' young ones," team owner Dietrich Mateschitz told autosport.com.
"In our case, with Christian not eligible for Friday testing, the rule contravenes its spirit."