Mercedes-Benz motorsport vice-president Norbert Haug has revealed that the battle to be Lewis Hamilton's team-mate next season could be between three drivers, now that several candidates have ruled themselves out of the running.

Nico Rosberg, Nick Heidfeld and even Fernando Alonso - if the rumour mill is to be believed - were all possibles for the seat alongside Hamilton in 2008, but have now committed themselves elsewhere, leaving two youngsters and a comparative veteran vying for potentially one of the hottest seats on the grid.

Speaking in an interview with Germany's Bild, Haug hinted that Heikki Kovalainen - the man ousted by Renault to make room for the returning Alonso - was definitely a candidate, but also suggested that Adrian Sutil and Pedro de la Rosa remained in contention. He also dropped a few other names into the mix - notably test driver Gary Paffett and DTM rivals Bruno Spengler and Paul di Resta - could also be considered, although they are unlikely to get anything more than a testing opportunity or try-out in McLaren's renowned simulator.

Kovalainen's exit from Enstone has elevated the Finn to the head of the race to partner Hamilton, although it is understood that he could also be a target for Toyota, which has yet to confirm veteran Jarno Trulli's status in the team.

Sutil, meanwhile, is the subject of mixed messages from Force India, where he was expected to stay for another season. Impressively fast, but occasionally wild, in his debut season under the Spyker banner, the German is a close friend of Hamilton's, which should ensure harmony at Woking, but is likely to command a high release fee from his current team. Force India team boss Colin Kolles has claimed, in different interviews, both that Sutil is staying put and that the team has two seats free for next season, keeping the German on the candidate list at McLaren.

de la Rosa remains a candidate too, thanks in the main to the group of sponsors assembled by McLaren to herald the arrival of Alonso twelve months ago. Committed for the length of the double world champion's initial contract, the likes of Santander and Mutua Madrilena are understood to favour de la Rosa's elevation from reserve.

Haug did not give a timescale for the decision, although it is expected to be clearer by the time that Formula One testing restarts in the New Year, in order for the team to fully integrate whoever is picked when the MP4-23 hits the track.