S?bastien Buemi may have moved ahead of GP2 Series rival Bruno Senna in the battle to secure a spot on the Formula 1 starting grid with Scuderia Toro Rosso in 2009, reports suggest.

A whole host of drivers have in recent weeks been linked to what could be two vacant berths at the Red Bull junior squad, with Sebastian Vettel graduating to the parent concern next season and no guarantees over the security of current team-mate S?bastien Bourdais' seat either.

Super Aguri F1 refugees Takuma Sato and Anthony Davidson are both believed to be in the frame - as are GP2 front-runners Buemi, Senna and the latter's Red Bull-backed, iSport International team-mate Karun Chandhok - with a test to be held at Jerez in southern Spain next month rumoured to be something of a shoot-out. Thus far only Buemi has been confirmed for the test.

"We believe that he is ready for the challenge and he is looking forward to doing well at the tests," Buemi's Bahrain-based uncle Humbert told the Gulf Daily News, adding that the 19-year-old Red Bull test driver is 'excited' about the forthcoming possibility.

Red Bull motor racing advisor Dr Helmut Marko is also clearly a keen fan of the Trust Team Arden star, urging STR co-owner Gerhard Berger to promote him to the top flight as being the only one of the GP2 prospects who is prepared for the task.

"Of the new generation, S?bastien Buemi is the only one who can say he is really ready," the Austrian told Swiss publication Motorsport Aktuell. "For the others, Formula 1 is still some distance further away."

It is widely-believed, though, that Senna is Berger's favoured option, with the ten-time grand prix winner having spent three seasons alongside the Brazilian's late uncle Ayrton at McLaren from 1990 to 1992.

The 25-year-old has insisted, however, that he is only interested in a long-term deal, stating that his management has been involved in talks with every F1 team save for Ferrari, with a race seat at STR or testing role at McLaren - with whom he shares the hotel chain Hilton as a key sponsor - understood to be the likeliest possibilities.

"I am seeking a long-term commitment," Senna stressed. "It makes no sense to look for something for only one year and then stand with empty hands in 2010."