Belgian GP: Mercedes and Ferrari to both debut new upgraded engines

Mercedes and Ferrari are set to introduce new upgraded engines at the Belgian GP as the championship battle hots up.

Both teams expect to run their respective 'Spec Three' power units from Friday's practice sessions onwards, and title rivals Lewis Hamilton and Sebastian Vettel will hope for what could be a pivotal engine boost.

"Naturally every upgrade that we have and every opportunity there is for an upgrade, it's important," Hamilton said.

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"[Spa and Monza are] the two big power circuits that we've got these next two weekends and you've seen how big an impact the power can make.

"This weekend I think they have got a new power unit, we will have a new power unit, so it will be interesting to see how they fare with each other."

There are still doubts over whether Valtteri Bottas will take Mercedes' new PU, however, as the Finn has already taken the maximum amount of engine elements this year.

Another power unit change, therefore, would automatically trigger a penalty.

"I think [Friday] morning we are going to know 100 per cent which engine we are going to start with," Bottas said. "If I am going to take a new engine there is going to be a penalty, that is something we'll find out.

"In any case, I think Spa would be one of the best places to take it as it one of the easiest places to overtake."

Mercedes last brought an engine upgrade at June's French GP, labelling the unit a 'Spec 2.1' after having to postpone its introduction due to quality issues, but team boss Toto Wolff has been eager to match Ferrari's power.

Ferrari have enjoyed an increase in speed in recent weeks, which is not believed to be solely down to the engine, but trialled their 'Spec Three' PU on the customer Haas and Sauber cars at the last race in Hungary.

Its successful debut means Vettel and Kimi Raikkonen will both fit the unit this weekend.

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