Hamilton and Alonso came to blows at Les Combes while battling for second place on the opening lap of Sunday’s Grand Prix at Spa-Francorchamps.

Contact between the pair sent Hamilton’s car airborne before it landed heavily on the ground, with Hamilton claiming he “almost broke my back coming down”.

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Hamilton was initially able to continue but was instructed to pull over and stop his car by Mercedes towards the end of the lap.

“Back off, no full load, part throttle, part throttle,” Hamilton was told by his race engineer Peter Bonnington.

Smoke was seen pouring from the back of the W13 after it came to a halt and Hamilton used a fire extinguisher to try and cool his overheating Mercedes.

A Mercedes spokesperson confirmed to Crash.net that the power unit and gearbox are currently undergoing inspection and assessment at their powertrains base in Brixworth.

Mercedes measured the impact at “over 40G” when Hamilton’s car hit the ground.

If the power unit has been damaged beyond repair, Hamilton may be required to take a new engine at this weekend’s Dutch Grand Prix.

Hamilton had moved onto his third V6 of the season in Belgium and Mercedes were hoping to get to the end of the year without incurring an engine penalty.

There are two other power units in Hamilton’s pool that could still be used, but they have racked up high mileage across the 13 races prior to Spa.

The introduction of a fourth ICE at Zandvoort would trigger a grid penalty for the seven-time world champion.

However, moving onto a third gearbox unit would not incur a penalty, should Hamilton require to do so.