Scuderia Toro Rosso has admitted that it unsuccessfully endeavoured to sign up Nelsinho Piquet and Juan-Pablo Montoya for 2009 - as S?bastien Bourdais' Formula 1 future hangs precariously in the balance.

The small Faenza-based squad currently has no confirmed drivers for next year following Italian Grand Prix winner Sebastian Vettel's graduation to Red Bull Racing and amidst continuing uncertainty over Bourdais' security at the team, and it has emerged that Piquet was a target before the announcement that the Brazilian rookie is to be retained by Renault for a second season.

More surprisingly still, team principal Franz Tost has now revealed that he also approached Montoya about the possibility of a shock return to the top flight. The 33-year-old Colombian triumphed in seven grands prix for BMW-Williams and McLaren-Mercedes over the course of his six-year F1 career, before acrimoniously walking away from the Woking-based outfit midway through the 2006 campaign to return across the Pond and compete in NASCAR.

"Unfortunately he no longer wants to be in Formula 1," Tost is quoted as having said by German magazine Auto Motor und Sport.

Whilst GP2 Series race-winners Bruno Senna and S?bastien Buemi, as well as Super Aguri F1 refugee Takuma Sato and possibly even Rubens Barrichello, are due to test for the Red Bull 'junior' outfit at Barcelona later this month, team co-owner Gerhard Berger has persistently refused to offer Bourdais any guarantees.

The Frenchman endured a torrid start to his maiden season in the uppermost echelon this year, but came on increasingly strong towards the end to the point where he was matching Vettel on a near-regular basis, and qualified inside the top ten for six of the last seven outings.

"He has talent," the Austrian ten-time grand prix-winner acknowledged when speaking about the record-breaking multiple Champ Car king, "but he lacks a bit of confidence both in the car and in himself."