Valtteri Bottas was left scratching his head after Sunday's Azerbaijan Grand Prix, and felt that a fundamental issue was behind his Alfa Romeo's lack of pace in Baku.
After a muted opening day of running at the venue, Bottas insisted that his team was on track for a step forward on Saturday.
Instead, the Finn took a step back, to the point where he was outpaced by Alfa teammate Guanyu Zhou in qualifying by over six tenths of a second.
That was a clear sign that Bottas was in for a difficult afternoon on Sunday, and indeed the Finn finished outside the top-ten for the first time since Jeddah and without a clue as to why his car had not been a top midfield contender as usual.
©AlfaRomeo
"I wish I knew, it almost feels like something is fundamentally wrong because we were so off the expected lap times and pace," he said. "Even Williams were faster than us at the end of the race which is not where our car should be.
"We changed from the old package to the new package for Saturday, and since then the issue started with the behaviour of the car. We'll have a look, I'm pretty convinced we'll find something.
"From Friday to Saturday, it just felt like we lost rear grip, which is a bit strange because with the parts we changed it should have been increasing the rear end. So we need to find out what's gone wrong.
"I had no chance to match Zhou's laptimes today, he was in another league, almost one second faster which for me is quite strange."
The fact that Zhou had fared better than his teammate in qualifying and on race day despite both drivers running the exact same specification led to suspicions by Alfa that a fundamental issue was embedded in Botta's C42.
"Since Saturday we started to have some question marks on Valtteri's car," said Xevi Pujolar, Alfa's
head of trackside engineering, quoted by Motorsport.com.
"And today it was clear that something is wrong. We need to understand what it is at the moment, but we can see that something is not right.
"Both cars are certainly the same configuration, I would say it's the same setup, everything was the same. There's something that was not working as expected."
©AlfaRomeo
With no time to conduct a forensic analysis before next weekend's Canadian Grand Prix, Pujolar said the Hinwil squad will need to swap as many components as possible on Bottas' car.
"Probably what will happen is that we'll have to change as much as possible to fix the problem, but that's the limitation we have got in such a quick turnaround," he added.
"So, we'll just try to change as much as possible to make sure that we start back to with our normal or expected performance."
Keep up to date with all the F1 news via Facebook and Twitter
