McLaren chief Zak Brown has stressed that the team’s return to Mercedes engines in 2021 will not be the sole catalyst to them winning races again in F1.

Amid what is proving their best season since their last with Mercedes power, 2014, McLaren last week announced a return to the German manufacturers’ power unit from the season after next when the team’s deal with Renault comes to an end.

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Brown, McLaren’s CEO, describes McLaren as being in a “momentum-building mode” and says the Mercedes deal will provide once further piece to the puzzle as they bid to return to the front.

Asked if the change in power unit would return them to winning ways, Brown told Sky Sports F1: “Over time, but I think it’s not power unit that’s holding us back from winning races right now, I think it’s ourselves.

“I don’t think we’re yet ready to win – it’s one step at a time. We’re having a good year and we just want to keep taking steps forward.

“In Formula 1 everything is about small incremental gains, but I think it’s not as easy as putting a different engine in and we’re back to the front. We’ve got a lot more work ahead of us than just changing engines.”

Brown added: “The chassis is good but I don’t think it’s as good as the three teams in front of us, quite frankly. We know where it has some weak spots on track.

“We have a new wind tunnel coming and I think we’re behind in some aerodynamic development, partially because we don’t have our own wind tunnel that’s state of the art. With Formula 1 it’s all a little bit everywhere as opposed to one specific area, so I think we’re making good progress.

“If you look at Mercedes, before they dominated they won a race and then you build momentum, so we’re just in a momentum-building mode right now.”

The winners of a combined 20 world championship titles last won a race in 2012 but their current fourth-place in the constructors’ championship is their highest placing since that season.

And Brown believes they can eventually challenge F1’s current world champions as an engine customer.

“I’m very confident that Mercedes supplies all the telemetry so it’s clear what’s in the Mercedes grand prix car is the same that’s in the Williams and the Racing Point cars,” said Brown to reporters.

“If we do a very good job with our team, execute, drivers do a good job, then I think we can. But you’re going to have to be on your A-game.”

And Mercedes boss Toto Wolff said: “If you see the guys that I’m at least interacting with – Andreas [Seidl], James Key or Zak – you can see that they are energised and they want to go back to where McLaren deserves to be. We are up for the challenge.”

McLaren reuniting with Mercedes power: The Q&A

When are McLaren switching to Mercedes engines?After one more year powered by Renault in 2020, McLaren will run Mercedes’ hybrid power unit from 2021.

How long is the deal for?The initial agreement is for a period of four seasons until 2024.

Why are McLaren going back to Mercedes?McLaren believe that while their time with Renault since 2018 has “given us a lot of power and their engine continues to improve” amid the Woking outfit’s rise back up the grid, Mercedes will help take them to the next level.

“We want to continue further up the grid and, quite simply, Mercedes has been the benchmark power unit during this hybrid era,” explained Brown. “The rules won’t really change much [on the 2021 engine] so we’re placing our bets that we think that’s going to be the power unit to have.”

Did they consider any other routes?Brown says the prospect of approaching Ferrari, who possess 2019’s standout engine, was never considered – pointing to a “clear brand clash” between the two makers of supercars – while building their own in-house power unit is not considered viable.

Didn’t Mercedes reject a McLaren approach before?In 2017, as McLaren and Honda prepared to part company, talks were held between the former partners, but an agreement was not reached.

“Back in the day Niki [Lauda] and I used to have big discussions around whether we wanted to supply other teams or concentrate on our own situation,” Wolff told Sky F1. “Since then times have changed a little bit. We believe that the learning curve is steeper with having more engines out there. You saw that we had some failures on Kubica’s car in Spa and Perez’s car in Monza and that is part of the learning process.

“It is a cash topic also – one more customer means better cash flow for Daimler overall – and we are up for the challenge. McLaren is a great team and a good group of people, but let’s go [for it].”

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What does it mean for the future of Mercedes’ own team?Nothing, according to Wolff, with the future of their involvement as a team owner beyond 2020 not linked to engine supply arrangements.

“One is not linked to the other,” Wolff told Sky F1. “I think we’ve got to see how Formula 1 develops and we are at a crucial time now to see where the regs go and how it all pans out. It’s a different topic to supplying customers, which is a standalone decision.”

Wolff also said in Sochi: “The [McLaren] relationship is pretty strong because of these days [1995-2014] but for us it was important to make clear that there is a works team today and this is a customer power unit relationship, and not the start of a works deal and us not being there anymore.”

So what now for Renault?As it stands, Renault’s own team will be the only one running the French manufacturer’s engine in 2021, whereas rivals Mercedes, Honda and Ferrari will all have at least two teams on their books.

But that’s not necessarily a problem according to their team principal Cyril Abiteboul. Looking at the regulations, if the effort of standardisation, simplification, aero rules, go ahead we believe that the two major performance differentiators will be engine, and engine integration and installation,” the Frenchman told Sky Sports at the Russian GP.