Klien (left) and Liuzzi are vying for one driving spot at Red Bull

Liuzzi was expected to step aside in favour of Christian Klien as part of Red Bull's driver rotation scheme which has seen each race three times in 2005.

But the Italian has been given an extra race before Klien takes over again for the Canadian Grand Prix next month.

However, the team have not yet said if Klien must surrender the drive again.

Red Bull sporting director Christian Horner said: "After having evaluated both drivers' performance during their three race stints, the team have decided that Tonio will continue as race driver at the next grand prix in Germany.

We have a very healthy situation, with healthy competition Christian Horner

"Christian will then be back in the race car from Montreal having made a valuable contribution to the team in the last three races as third driver."

The duo share the second seat behind principal driver David Coulthard and have so far had three chances to prove their ability behind the wheel.

"Christian did very well in his three races before Tonio came in," said Horner.

"So we have a very healthy situation, with healthy competition."

Horner said he had been impressed by Liuzzi, who is taking part in his first Formula One season after winning the Formula 3000 title.

"I think for a rookie he's done an excellent job so far," said Horner. "So far we are pleased with him."

Klien, who joined Red Bull last season, claimed a total of three points this campaign before Liuzzi stepped in.

The Italian has made less of an impression, and has not been as close a match for lead driver David Coulthard as Klien.