Jenson Button will likely have to wait until the Mexican Grand Prix to receive his latest update of engine from McLaren's Formula 1 power-unit supplier Honda.
As revealed by Autosport, Honda introduced for this weekend's Russian Grand Prix a new specification of engine on Fernando Alonso's McLaren, spending its final four development tokens, and incurring a 25-place grid penalty.
McLaren-Honda and Alonso ran the package in first practice at the Sochi Autodrom before then switching to a previously used system for practice two, but with a new turbocharger and MGU-H, collecting a further 10-place penalty.
Alonso will now use the upgraded engine for the next grand prix at Austin.
Honda will produce Button's system as quick as is humanly possible given the time it takes to manufacture the parts.
While it is extremely unlikely the 35-year-old will have the engine on his car for America, it is hoped it will be in place for the race a week later in Mexico, with the latest date being Brazil.
Confirming the situation, Button said: "It [Alonso's new engine] is not actually for this weekend as such.
"The updated engine is for another race. Yes, he will have it for that race and I won't.
"We need to get it on one of the cars and see what it gives us, and mine will follow the next grand prix after that."
Although Button would prefer a level playing field with Alonso, he appreciates circumstances have dictated matters on this occasion given the difficulties Honda has endured this season, and as it prepares for 2016.
Button added: "In a team you like to keep it equal, but in the position we're in we need to get the engines in the back of the car.
"We need to do a lot of mileage to see how it is for the future, for next year. The next few races are going to be testing for us.
"They're going to be very difficult. The only race we could have a chance of doing OK is Austin, and after that this car is a test bed.
"We're doing our best to get everything out of the car and to get the best result possible.
"But simply it will be a lot of testing for us and doing things that maybe you wouldn't normally do in the season with the car and the engine to make sure you are in the right place for next year."