Niki Lauda belives that Ferrari's power unit has now matched Mercedes own level of performance on the engine front.
The Mercedes AMG Petronas non-executive chairman believes the Scuderia has enjoyed a substantial step forward this season, punctuated by the introduction of an upgraded power unit at the Italian Grand Prix which has now wiped out the German manufacturer's power advantage.
"This year to do better than Ferrari we had to make a lot of progress," Lauda told Italy's Autosprint magazine.
"Since they introduced the updated engine at Monza, I would say that they matched us in terms of power and efficiency. The 20bhp advantage we had is now gone. We are now at the same level of power: we know for certain because of the reference we have."
Lauda is now convinced that Mercedes will be hard pressed to repeat in 2016 the dominance it has enjoyed this year and last, with the Maranello squad clearly threatening its authority.
"The picture will change in 2016, because in F1 you can't sustain your technical superiority for a long time," Lauda concluded.
"We know the others can catch up. When you are at the limit of the performance of the regulations it's difficult to make big progress, which is easier for those behind us."
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