Charles Leclerc and Ferrari were left baffled by inconsistent performance during the Spanish Grand Prix.

The Monegasque started Sunday's race from the pit lane after only qualifying 19th with an unusual issue that he claimed impacted him only in left-hand corners.

Despite finding no obvious problems in an inspection, Ferrari took the chance to fit a new rear end onto Leclerc's car plus new power unit components, triggering his pit lane start.

In the race, however, Charles could only improve to 11th as the Scuderia's weakness with tyre wear was exaggerated by the high-speed Barcelona track.

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Even more concerning, however, was the fluctuation in pace from the SF-23.

"I don't understand what we are doing wrong, but we are doing something wrong," Leclerc stated.

"In terms of balance, the car was alright, but the performance was not at all consistent.

"We ran the same tyre twice in the same race, and we went from having a very bad car to quite a good one towards the end of the race.

"We really must analyse all the data because while the upgrades seem to work as expected, we are always slightly caught out by what is happening with the tyres and we struggle to get them in the right window which is a big problem.

"Now we will go back to the factory and find out what went wrong yesterday in qualifying because that’s what put us in a tricky situation today. There’s a lot of work to do."

Ferrari has had a problem with a 'peaky' car throughout 2023, which means the drivers lack confidence even corner-to-corner, particularly over a race stint.

And addressing the narrowness of that performance window is now a key priority for team boss Fred Vasseur.

“It’s very difficult to understand and to fix it because it’s not always the same problem,” the Frenchman explained.

“We are there in qualifying and we are not there in the race. We are inconsistent on the same car between compounds and sometimes between the same compounds.

“Perhaps we can steer a little bit of the development towards the consistency, to have something a bit easier to drive and so that we can steer a bit.

“It’s the direction that we took the last couple of months or weeks and I think that we are a bit more consistent than we were at one stage.

“The issue is more than on the chassis side, the issue is more from stint to stint because if you had something like this you could say that it’s always there.”

Last weekend also saw Ferrari introduce a new upgrade, including a shift in its sidepod design to incorporate more downwash, a trend that was pioneered by Red Bull.

And Vasseur remains confident that the Italian team can emerge from its current woes.

“The potential is there and sooner or later we will be able to unleash that potential by better understanding the tyres and tyre management," he added.

“We must focus on our work and what we have to do.

“We have taken out the positive and the negative, at least I think we have a clearer idea of ​​what we are doing well and what we have to work on, we must not be soft on our analysis.”