Who will fill the final seats on the F1 grid?

With a month to go before the start of the new car testing season and two months to the first race there are still two race seats available. Many seats were filled in the weeks leading up to Christmas with Lotus Renault, Toro Rosso and Force India filling in their entry cards.

But what of Williams and HRT?

The contenders for Williams seem quite straight forward; Rubens Barrichello is the choice of the Williams engineers, who rate the Brazilian highly and were pleased with his performances in the closing stages of last season. Meanwhile Adrian Sutil has experience, is fast and brings some sponsorship budget. He had some strong performances in the closing races of the season.

However Auto Motor und Sport in Germany is reporting that Sutil wants only a one year contract to keep his chances open of taking Felipe Massa's seat at Ferrari in 2013.

Whether those chances are realistic time will tell, but it does seem likely that there will be a seat alongside Fernando Alonso in 2013, with Ferrari likely to want someone who is fast and consistent enough, but who would keep the seat warm in anticipation of a bid for Sebastian Vettel at the end of 2014, when his Red Bull contract expires.

According to AMuS, Sutil's position makes Barrichello's Williams candidacy pretty strong, but time will tell. The Brazilian has not always seen eye to eye with team boss Adam Parr. Meanwhile veteran technical boss and team co-founder Patrick Head has stepped down from the board and will henceforth focus his attentions on Williams' hybrid power business.

HRT has a space to fill alongside Pedro de la Rosa. The team which is becoming increasingly Spanish, appointed Luis Perez Sala as team principal just before Christmas, cutting ties with Colin Kolles. Sala is a former Minardi driver, who has been acting as a consultant since the summer.

It's clear that the team will need a driver who brings a budget in the seat. Jaime Alguersuari has a father who is a powerful figure in Spanish motorsport circles but whether that could lead to a budget big enough to trump others will have to be seen. Bruno Senna had an unhappy time with the team when Kolles was in charge and it's not clear whether he would see a return there, even under different management, as a worthwhile step to stay in F1. His name has been linked with Williams too, but not so much in recent weeks. Narain Karthikeyan also has some budget.