Fernando Alonso says his car's set-up for Monaco Grand Prix qualifying was like "tossing a coin" after admitting his McLaren Formula 1 team was lost in final practice.
Alonso, who missed most of the first practice session on Thursday due to brake issues, finished FP3 down in 15th position, saying his car's handling felt "very strange".
The team made several changes to the car's set-up ahead of qualifying and Alonso managed his best qualifying effort of the season with seventh position.
Alonso admitted the set-up changes were a gamble and was delighted they had paid off.
"It's been a very complicated weekend," Alonso said. "We lost the first session because of the brakes and in the third one the car was handling very strange.
"The rear felt disconnected from the front. We had problems on the rear in the slow corners and in the fast corners we had problems on the front and that's usually a puzzle that's hard to solve.
"We made a lot of changes to the car and we went out in qualifying like tossing a coin to see how the car would handle.
"We saw quickly that it was a different car, that was handling better and giving me the confidence to attack. Seventh tastes very good now."
The McLaren driver reiterated his belief that managing the hypersoft tyres will be the key to the race, after Pirelli's softest rubber has degraded more than he expected since the start of the weekend.
Alonso, like all drivers in the top 10, will start the race with the pink-sidewalled tyres and it is widely expected that the whole field will attempt to stop just once.
"I think the question everybody is asking is the hypersofts, how long they will last and how much trouble they will cause," the Spaniard added.
"They are not going to pass you, that's for sure, but how long you stay out is always a risk.
"If someone stops and undercuts you, then it's going to be tough. And if you stop early and you are behind a car doing 65 laps on the hard tyre, then you are stuck for 64 laps behind it."
Alonso's teammate Stoffel Vandoorne missed the top 10 shootout and qualified down in 11th position.