McLaren on Friday said they would drop Honda engines in favour of Renault at the end of this season, ending a troubled partnership with the Japanese manufacturer as they bid to return to the top of Formula One.
The celebrated British marque announced a three-year deal covering 2018, 2019 and 2020 with France's Renault, who simultaneously unveiled a split with Toro Rosso -- who will now be powered by Honda.
The related moves, which had been widely flagged, could ultimately herald a shake-up in the pecking order of Formula One, which is currently dominated by Mercedes and Ferrari.
Honda's exit is likely to convince two-time world champion Fernando Alonso, who has repeatedly threatened to quit over the misfiring Honda engines, to stay at McLaren next year.
As part of the deal, Toro Rosso loaned highly rated Spaniard Carlos Sainz to Renault for 2018, where he will partner Nico Hulkenberg -- with Britain's Jolyon Palmer elbowed out.
"Today's announcement gives us the stability we need to move ahead with our chassis and technical programme for 2018 without any further hesitation," said McLaren executive director Zak Brown.
Britain's most successful Formula One team have failed to win a race since 2012 and are a long way from challenging Mercedes, Ferrari or Red Bull.
The vexed collaboration with Honda came to a head this month in Italy as Alonso and Stoffel Vandoorne both collected grid penalties and failed to finish.
Vandoorne was penalised before the race after being fitted with a brand-new engine -- and still suffered a power failure.
Honda have been a part of Formula One as a constructor and engine supplier -- on and off -- since 1964, but they have struggled with current regulations which require a hybrid, part-electric power unit.
- Woeful sequence -
There was no word from Renault or Red Bull on their future together, following reports that the French manufacturer will walk away from their partnership after 2018.
Red Bull and Renault have also been at odds over the complex hybrid technology, whose introduction in 2014 coincided with the end of their four-year hold on the drivers' and constructors' world championships.
Honda's best finish in the constructors' standings was fourth, in 1967 and 2006, but they powered McLaren and Williams to a string of titles in the late 1980s and early 1990s when Alain Prost and the late Ayrton Senna dominated F1.
The Japanese car-making giant pulled its team out of the sport in 2008 to cut costs to combat the global economic crisis before being saved by a management buy-out led by team principal Ross Brawn.
Since Honda teamed up with McLaren in 2015, the best finish by one of their drivers has been sixth, a woeful sequence that has dealt a serious blow to their reputation.
They will now try their luck with Toro Rosso, Red Bull's junior partner who admitted the timing of the announcement, late in the season, was far from ideal.
"There are some challenges to face given the time of year but Toro Rosso has faced many difficult tasks with timing in the past and has the flexibility to deal with it," said Toro Rosso's technical director James Key.