Liuzzi is to get his chance to race alongside Coulthard

The move comes despite Klien's impressive performances compared to lead driver David Coulthard since the start of the season.

Red Bull sporting director Christian Horner said: "Christian has performed faultlessly in the first three races.

"This decision is simply an opportunity to evaluate his counterpart."

Red Bull described their policy as a "three-race trial" for Liuzzi, the Formula 3000 champion, and a chance for him to "gain experience".

They did not say what would happen in the subsequent races.

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Klien has outperformed 13-time Grand Prix winner Coulthard in qualifying in two of the three races so far, but he insisted he was not disappointed to be standing down.

"Coming into this season it was always made clear to me that Tonio would get his opportunity to race," Klien said.

"I feel that I have done a good job in the first three races and I am pleased with my performance, qualifying no lower than seventh in all three races and scoring points in Australia and Malaysia.

"As a racing driver, of course I want to race and I am sure I will find it very difficult to watch from the pits.

"But I have always understood the reasons behind this strategy and I am comfortable with it."

Klien will have to watch the next three races from the sidelines

Klien will not be able to fulfil the role of third driver in Friday testing, which Liuzzi has done since the start of the season, because he is ineligible having raced last season.

Red Bull said they would announce at a later date who would be third drive at the next race at Imola, the San Marino Grand Prix.

Coulthard said: "Christian will naturally be disappointed not to be driving in Imola, but he can be very satisfied with his 'coming of age' as an F1 driver.

"As it was clear that they would be sharing the car from the start of the season, it makes sense for Tonio to make his debut in Imola, a track he knows and has won at in F3000."