Fernando Alonso will stay at McLaren-Honda if the team wins by September, but has refused to give a more definitive answer on his plans for 2018.
"We have to win," he said when asked what he will do when his current contract expires at the end of the year. "If we are winning before September or something like that, I will make a decision and I will stay."
The team's struggle for points so far this season -- let alone wins -- means a victory in the next three months is extremely unlikely. Yet Alonso's options in Formula One for 2018 appear to be limited, with top teams Mercedes, Ferrari and Red Bull all unlikely to offer him a drive.
Within McLaren, the pressure is growing on engine supplier Honda, with executive director Zak Brown saying his team is at a "fork in the road" over its plans for the future. But with reliability issues hampering the team at the last race in Monaco and a planned upgrade for this weekend's Canadian Grand Prix being pushed back, a quick fix is looking less and less likely.
Pushed on whether he would quit McLaren if the team does not win a race by September, Alonso added: "You cannot be 100 per cent [sure] now in June about a decision for next year that I haven't even started to consider.
"What we all want is to win and I think related to the answer before, what Zak commented about yesterday and the Honda thing -- it is probably what you would expect for Zak to say. He wants to win, he wants to put McLaren again on a contender position for the championship, so after three years we are not in that position and things have to change for the team. It's the same with me.
"I want to win, and during this project I wanted to be world champion and we are not in that position. So if you don't see things changing and you are not in a competitive position, maybe you change project.
"That's the only thing I can say now until I sit down with myself in September or October -- after the summer, as I always said. I cannot say 100 per cent about anything now. I'm very open and I will hopefully take the best decision after the summer."
Alonso's recent participation in the Indy 500 has added another element to his future plans after he expressed his desire to become the first driver in the modern era to win motorsport's Triple Crown -- the Monaco GP, Indy 500 and Le Mans 24 Hours. He insists another world championship in F1 is still his primary goal, but added that he is "not afraid" of a future outside F1.
"As I said many times, a third world championship in F1 is still my biggest priority. I think I developed my skills to drive F1 cars for the last 16 years, so the best car that I can drive is still a Formula One car. But at another time I can jump in any car, in any category, with any tyres, with any rules that I go there and I'm competitive.
"I'm not afraid of the future, if I cannot succeed here and win the third world championship I still love motor racing and I will race in any series. And I know that I can win in any series."