Mercedes have been dominating Formula One in both the drivers and constructors' championships in recent years and have continued to do so this term as well.
In 2017, though, they are behind Ferrari, who have been able to match them in terms of pace and durability throughout the 13 rounds so far.
Red Bull, impressive for four successive seasons from 2010 to 2013, have had underwhelming campaigns since their last title victory.
Team boss Christian Horner has given his insights into the matter of why Mercedes and Ferrari powered engines are outlasting others throughout the course of the season.
Speaking to Sky Sports F1, the 43-year-old said he believes the supremacy of the title contenders are set to last until engines rules are modified in 2021.
Renault and Honda have struggled to rival their peers, consistently suffering with reliability issues, while both Mercedes and Ferrari are miles ahead.
Horner said: “We'll never accept that we can't be competitive so we'll keep pushing and keep developing and try and make up whatever horsepower deficit there is on the chassis side.
“But the reality is, those two manufacturers [Ferrari and Mercedes] have such a march, such committed investment, it's difficult to see how the others will catch up in the intervening period between now and 2021.”
F1 Grand Prix of Italy – Practice
Horner has previously voiced his concerns regarding the hybrid turbo engines introduced in 2014 and he maintains his stance in the present scenario, stating the move has not done anything positive for the sport.
Formula One will continue with the current setup until 2020 with speculations and talks of future plans already in motion.
In view of making the engines cheaper and less complex, Porsche have confirmed their interest for a possible return, whereas, Aston Martin, who work with Red Bull on a hypercar project are also in the mix alongside Lamborghini, according to the British supremo.
F1 Grand Prix of Italy
“We may well [lose manufacturers] but I think there are iconic manufacturers who would be keen to come in if it was affordable.
“Aston Martin being one of them, Lamborghini attending meetings. So long as you have Ferrari there, so long as you have historic teams like McLaren and Williams and so on, and other manufacturers like those I've mentioned were to come in. I think it's all about the spectacle.
“Manufacturers have always come and gone in F1 whenever it's suited them. I think the most important thing is to get the product right, get the show right, and then it's up to the manufacturers to be there or not.”
F1 Grand Prix of Italy
Red Bull are powered by Renault engines and have tried their best to match their counterpart but have fallen short on most occasions.
The rivalry resumes on September 17 at the Marina Bay street circuit in Singapore.