With the German car manufacturer locked in a tight fight for the Formula 1 title with Ferrari, it has decided to unleash its latest power unit for the high-speed Spa circuit.

Although Mercedes had been tight-lipped about its plans ahead of track action beginning, a note issued by the FIA on Friday morning confirmed that both Lewis Hamilton and Valtteri Bottas were fitted with new internal combustion units, turbochargers, and MGU-Hs.

It is understood that the upgrades do bring performance benefits to what is already believed to be the benchmark power unit. A previous update to the Mercedes had been solely focused on reliability improvements.

Although there are nine races still go to this season, Mercedes believes that it can shuffle around its current pool of engines to ensure both drivers can see out the campaign without the need for any more components that would result in a penalty.

Mercedes is expected to hold the edge at Spa this weekend, thanks to the aero characteristics of its W08, although it is taking nothing for granted.

Bottas said ahead of track action beginning: "I think we are more confident coming to this race than, for example, a track like Budapest. I think we have seen that on the very high downforce tracks Ferrari is very strong.

"They've been not bad at any circuit so we don't feel that we are favourites or anything but we feel we can be reasonably strong here and I'm sure it's going to be another tight battle."

Rival Ferrari is sticking with its third engine for now, with the team working on a performance upgrade that could be unleashed as soon as the Italian Grand Prix to help it maintain its title battle.