F1 2010 hopeful Stefan GP has been forced to abandon its plans to test at Portim?o in Portugal this week after proving unable to secure a supply of tyres from the sport's official partner Bridgestone - but team founder Zoran Stefanovic has confirmed that the Serbian newcomer's driver line-up is now rapidly taking shape.

Stefan GP has acquired the ready-designed Toyota TF110 chassis' and has been allowed to make use of some of the Japanese manufacturer's Cologne base for the forthcoming campaign, but the sole sticking point is that it still has no entry, given that the 13 permitted slots are all currently filled - the F1 equivalent of being all dressed up but with nowhere to go.

However, financially-troubled American operation USF1 has sought special dispensation from governing body the FIA to miss the opening four flyaway grands prix [see separate story - click here] - as it battles both to secure sufficient funding and also produce a chassis to accompany its Cosworth engine this year - a request that is in clear contravention of the binding Concorde Agreement to which it has already committed. Crash.net understands that another of the Charlotte-based concern's original backers - Swiss investment firm Locstein AG - has now similarly deserted the beleaguered and considerably-maligned squad.

With Stefan ready and waiting to fill the void in the event of - as looks increasingly likely - USF1 being unable to make the grade, and with the Belgrade-based outfit also benefitting from the support of the sport's highly-influential commercial rights-holder Bernie Ecclestone, it appears now that it may be a matter of 'when' rather than merely 'if' one team is ejected to make way for the other, meaning that in the bigger picture, the test cancellation is simply an unfortunate blip.

Bridgestone is contractually permitted only to provide tyres to teams that have an official world championship entry - meaning there is no obligation on the company to aid Stefan's plight. Despite what is incredibly the first setback in the team's impressive eleventh-hour preparations for what it hopes will be its maiden campaign in the top flight, everything else is seemingly progressing apace.

With former McLaren-Mercedes chief designer - and 'Spygate' protagonist - Mike Coughlan already hired and the confirmation of ex-Williams ace Kazuki Nakajima in one of the two cockpits, ostensibly as part of the deal with Toyota, Stefanovic has confirmed that negotiations are nearing agreement with 1997 F1 World Champion Jacques Villeneuve to occupy the second berth.

Stefan GP has also sent containers of team equipment to Bahrain for the season curtain-raiser in Sakhir, and has revealed that even if it is unsuccessful in gaining a spot on the grand prix grid in 2010, it will continue to push ahead and test during the year to be ready to try again in 2011.