After Bruno Senna's move to fill the vacant Williams seat, there is now only one seat left on the Formula 1 grid for 2012 - which is at HRT, one of the least attractive teams on the grid for drivers.

Surely Luis Perez-Sala himself will be wondering who will follow in the footsteps of Bruno Senna, Karun Chandhok, Sakon Yamamoto, Christian Klien, Vitantonio Liuzzi, Narain Karthikeyan, Daniel Ricciardo and the team's first driver for 2012, Pedro de la Rosa, having already had a couple of knockbacks from drivers.

So lets see the list of drivers without a drive in F1 for this coming season who were racing last season.

There is Vitaly Petrov and Nick Heidfeld from Lotus Renault GP, Jaime Alguersuari from Toro Rosso, Rubens Barrichello from Williams, Adrian Sutil from Force India and Jerome d'Ambrosio from Marussia Virgin.

Let's start with Petrov. He has been strongly linked to Caterham after his contract at Lotus was ended early and if Caterham were an option for 2012, would he want to take a step backwards to HRT? Perhaps the best chance for the Russian is a third driver role somewhere on the grid to focus on 2013.

Not much has been said on Heidfeld since he was replaced in the Renault line-up by Bruno Senna at Spa back in August. As it stands, the German is unlikely to see HRT as a realistic option if he wanted to remain part of the F1 scene.

Alguersuari has already ruled out HRT so no elaborate discussion is needed about the former Toro Rosso man, who like Petrov, could be a good choice for a team seeking a test and reserve man.

Barrichello has the racing passion to try and carry on into a twentieth season, but would the Brazilian want to move to HRT - especially after his tough 2011 with Williams? Maybe the time has come to go out with dignity rather than try to move his career past 326 races...

Sutil's position is complicated by his upcoming court case as - if charged - he could face jail and be banned from Chinese soil. With his focus on the case at the moment, he is another driver who may be more likely to end up in a third driver role this year to try and get into a better race seat in 2013.

D'Ambrosio would appear to be the driver most likely to take up a drive with HRT, but he has been linked with roles elsewhere that could be more beneficial for his future career.

On top of all that, we've seen drivers like Karun Chandhok sign up for sportscar programmes and testing roles after finding themselves unable to move into an F1 race seat, with the prospect of others following suit - Sebastien Buemi being one example.

Gone are the days where a team took on a third driver who wasn't quite as good as its race drivers, because F1 is now so competitive.

2012 should be just as competitive, although don't expect HRT to be winning a race anytime soon. As a result, who fills the second seat remains to be seen...

by Cameron Paterson