Jenson Button described McLaren as its "own worst enemy" as a fuel pump problem prevented a strong showing in the last segment of Monaco Grand Prix qualifying.
After finishing fifth in Q1 and eighth in Q2, Button was unable to mount a proper challenge in Q3, thanks to what was later revealed to be an issue with his car's fuel pump. He wound up ninth, two spots behind his McLaren teammate Sergio Perez.
"I think we did a good job in terms of getting out on the right tires at the right time and the pace was good, but it doesn't really matter when you have an issue at the end," said Button.
"I'm ninth and that's it. We're our own worst enemy, it seems. You eventually get the car working well and we've done everything right this weekend and then you have an issue like that in Q3. It's not easy at the moment."
Button predicted that making progress in the race will be difficult.
"I think getting in the top five from being ninth will be a massive difference. But when you want to do your own strategy and ideas in the race, you can't if you're teammate is ahead of you. So it's going to be a tough afternoon."