Fernando Alonso will use a Chevrolet engine for his bid to win the Indianapolis 500 next year, his McLaren team have confirmed.
The announcement was a formality because Honda, the only other engine manufacturer in Indycar, had refused to supply an engine for Alonso's car.
The two-time Formula 1 world champion will have the engine that set pole and won the prestigious race in 2018.
Alonso, 37, retired from F1 at the end of the 2018 season with 32 victories.
The Spaniard has set himself the target of winning motorsport's unofficial triple crown, of the Monaco Grand Prix, Le Mans 24 Hours and the Indy 500.
Alonso won Monaco twice - with Renault in 2006 and McLaren in 2007 - and triumphed at Le Mans on his first attempt this year in a Toyota with co-drivers Sebastien Buemi and Kazuki Nakajima.
Only Graham Hill has won all three events.
- Fernando Alonso: The F1 great who couldn't catch a break
- McLaren's Spanish driver to retire from Formula 1 at end of season
- 'Fernando Alonso is an unbelievable talent - F1 will be a poorer place without him'
Some regard the triple crown as the F1 world title, Indy and Le Mans - but both Briton Hill and Alonso are double F1 world champions anyway.
Alonso is contesting Indy with a car run by a new team being set up by McLaren. Former Force India deputy team principal Bob Fernley is leading the project in his new role as McLaren Indycar president.
Fernley said: "Our partnership with Chevrolet is a key piece of our plan for the 2019 Indy 500.
"As the reigning winning engine, the Chevrolet motor puts us in a strong position to contest this incredibly challenging event.
"We've quickly established a strong working relationship with the Chevrolet team, who are absolute professionals, committed to the challenge, and true racers."
Alonso raced at Indy in 2017, leading 27 laps and contesting victory until his engine - that time a Honda - failed in the closing stages. He won the rookie of the year award.
The Spaniard is also hoping to become World Endurance Champion at the end of the current 'super-season', which runs until next year's Le Mans.
He is also competing in the Daytona 24 Hours sportscar event on 26-27 January in a Cadillac for leading outfit Wayne Taylor Racing.