McLaren face a "critical" season in 2018 as they look to achieve success with Fernando Alonso and a Renault engine, according to Zak Brown.
The team finally confirmed at the US GP that Alonso is staying on for 2018 to partner the fast-improving Stoffel Vandoorne, with the two-time world champion convinced McLaren can return to the podium now they are swapping Honda for Renault power.
McLaren have gone 74 races without a top-three finish and Brown, who admitted it would have been a "big blow" had the team lost Alonso, acknowledges that 2018 now represents a defining season.
"Next year is critical," admitted McLaren's executive director.
"I'm not sure about the term 'make it or break it', but clearly we have the drivers we want, we've got a very good power unit, we've got a great team.
"We've been given the resources we need to have a competitive race car, so next year is critically important to show that we are a front-running team that so many people know we are."
Despite admitting to doubts earlier in the year about whether he wanted to continue in F1, Alonso says he chose to stay at McLaren because he can see the potential of the team and their new Renault engine supply.
Asked if he remained confident he could win his third world title at McLaren, Alonso replied: "That's why I stay.
"Even after Indianapolis in June and July, I was thinking what the best option for me for next year was because I don't like too much to be out of Q3, I don't like too much being out of the podium. So I said if that will be the case next year it's better to look outside Formula 1 maybe to experience the podium celebrations and those victory tastes.
"But we've made a lot of progress this year, I've been in the factory a lot. I know what is in the plan for next year and I know what Renault is preparing for next year. So I'm here because I believe I can be on those podium celebrations and in those moments."
Alonso's new McLaren deal includes a provision for him to compete in non-F1 events and although the Spaniard has ruled out an immediate return to the Indianapolis 500 in 2018, speculation has already stated that he could race in the Le Mans 24 Hours in June instead.
Put to him that the endurance race could be an option next season as it does not clash with a Grand Prix, Alonso said: "I didn't talk to anyone yet, but definitely it's something that if it comes I'll try and exploit that opportunity.
"Together with McLaren, if that's something that makes sense, as we did with the Indy 500 this year, we will try to do it.
"But at the moment there is nothing new planned."