Toto Wolff says Mercedes will be prepared to run three cars next season should Red Bull, Toro Rosso and Red Bull be forced out the sport, but he insists the priority is to prevent them from exiting.

As per its sporting and commercial agreements, F1 must field a grid of no less than 20 full-time entries or be forced to enact a motion to request certain teams to begin running three cars, starting with Mercedes, Ferrari, McLaren and - ironically - Red Bull.

Though this was raised as a distinct possibility last season when Caterham and Marussia folded towards the end of 2014, the latter's return as Manor avoided that enforcement.

However, with Red Bull and Toro Rosso now at risk - as well as Lotus if its sale to Renault doesn't follow through -, at worst F1 faces the loss of six cars from its grid and only two to take their place from the incoming Haas team.

Indeed, though Mercedes has had an indirect hand in Red Bull's potential exit over its refusal to supply engines next season, Wolff hinted that Mercedes will prepare for every eventuality if the teams withdraw.

"If a team would leave, and we had this discussion about Lotus a while ago, third cars are a solution to fill up the grid. For me personally it is a pretty exciting idea.

"I'd rather have Red Bull in the sport than third cars and a grid of 27 or 28 cars and some exciting young drivers in those cars, but this is definitely one of the fall-back solutions. I think priority number one is to keep them in the sport."