Jenson Button did not take part in qualifying for the Mexican Grand Prix after the team failed to fix a problem with his Honda engine.
Button was due to start from the back row of the grid regardless after taking two new power units this weekend and receiving the associated penalties. McLaren was hoping to use one engine in FP1 before saving it for the final two rounds and the second for the remainder of the weekend, but problems with both power units means it is now just focusing on getting ready for Sunday's race.
"The underlying signal problems on JB's engine have not been resolved," the team confirmed on Twitter. "Therefore, he won't take part in quali. Our focus is now on the race."
Button added: "All weekend it's been tough, we've had a lot of issues. I've done hardly any running really. It's tough, we had a systems failure with this power unit so it means that we have to revert to the other power unit for the race, so I miss qualifying.
"But we were eighth and ninth in FP2 with limited running so it's definitely getting there but obviously we have other issues. But I would still rather have some reliability issues and have power, so I'm not too disappointed."