Lewis Hamilton has said the changes the team made to his Ferrari between the sole practice session and Saturday's sprint race ultimately "flipped the car on its head."
The seven-time world champion qualified down in fifth for Sunday's Dutch Grand Prix and has spent the weekend trying to eek as much performance out of his car as possible.
Even though he finished Friday's practice session in the top four, he felt like there was more he could improve, but it didn't quite go as planned.
"I'm grateful that I was able to [qualify fifth] because I think I was at P8 or something and my heart sunk at that moment, but a much different session, a much different car," he told Sky.
"In practice, the car felt great and was consistent but there are always areas you feel you can improve so we made subtle changes to try and fix those improvements and it flipped the car on its head and it was horrible through sprint qualifying and the sprint.
"I had no confidence in the balance and we made all these changes into qualifying, so I was learning a new car again."
Hamilton currently sits second in the drivers' championship, 53 points adrift from Mercedes youngster Kimi Antonelli.
The Brit has been having a much improved season compared to last, and took his first race win in red at the Barcelona-Catalunya Grand Prix in June.
- Max Verstappen deal: Good news for Red Bull and F1, bad news for the driver market
- Lando Norris on his McLaren: 'Nowhere near good enough' to fight for title
- Dutch Grand Prix: George Russell takes third sprint race victory of the season
He remains optimistic for Sunday's race and feels they will be able to keep up with pole sitter Lando Norris in the McLaren, along with George Russell, Antonelli, and Oscar Piastri ahead.
"I think our race pace was better today. It was good," Hamilton said. "Mine wasn't great, but Charles' [Leclerc] particularly was good, and I think the car feels much better. I think it's going to be better tomorrow. So, I think we'll probably be able to hold on to the guys up ahead at least. Strategy is going to be key."
His teammate Charles Leclerc qualified for the grand prix one position behind him in Zandvoort and had similar difficulties with his Ferrari.
"I think we changed a bit too much of our power strategy throughout qualifying and then getting to Q3," he said.
"I've had some weird things going on so we lost a bit of performance there. I had no time during qualifying for the potential for pole."
