Mercedes driver Nico Rosberg will have to serve a five-place starting grid penalty for tomorrow's Belgian Grand Prix in Spa following a gearbox failure in practice.

"Nico will take a five-place grid penalty for a gearbox change after this morning FP3 issue," the team confirmed via their Twitter feed.

Drivers receive a five-place grid penalty if they change their gearbox before it's completed the required lifespan of five consecutive races.

Rosberg had also received a grid penalty in July for his home event, the German Grand Prix at Hockenheim, after a problem was found with the gearbox used at the previous British GP at Silverstone.

The latest gearbox issue means Rosberg joins Mark Webber on the 'naughty step', as the Red Bull also had to make a gearbox change following the end of the Hungarian Grand Prix and has been handed a similar five-place grid drop. (See separate story.)

Rosberg's gearbox issued happened in the full glare of the TV coverage of the final Free Practice 3 session in nearly dry conditions at Spa-Francorchamps on Saturday morning.

Roberg's car stopped early in the session after he'd managed just five laps before he was forced to pull over to the side of the circuit and park, meaning that he lost almost all of his final chance of getting some track time after Friday's near-washout due to the weather.