Fernando Alonso has said that McLaren-Honda's ongoing struggles in Formula 1 are "tiring".
The Spaniard skipped Monaco to do the Indy 500, but will return to his regular Formula 1 duties next weekend in Canada.
"I'm happy, the only thing missing is to be competitive," Alonso told EFE news agency.
"With Honda and the engine we have we cannot get all the potential possible, and this is sometimes frustrating. Because you try to give everything you have in a weekend and then something breaks, it's a little tiring."
Retaining Alonso beyond his 2017 contract has been identified as a priority by McLaren-Honda, but the team cannot afford more lacklustre seasons for other reasons as well.
Team executive Zak Brown is quoted by Marca sports newspaper as saying: "We have to solve our problems.
"2018 is not far away so we're going to have to evaluate how we get back to the top positions.
"I don't know yet how we are going to do it, and it's certainly very difficult to imagine that we are going to fight for the world championship next year.
"But we can take a big step and we need to find a way to be in that position. We still have a little time before the summer break."
The team remain pointless at the bottom of the constructors' championship ahead of the race in Canada.
