"We are missing pure power," admits Fred Vasseur as Ferrari's ADUO upgrade fails to impress.

While impressive on Friday, as the weekend wore on it became painfully clear that Ferrari's new power unit, part of the second round of the controversial ADUO system, was actually losing ground to its Mercedes rivals.

Though Charles Lecelrc and Lewis Hamilton qualified fourth and fifth, both over 0.2s off the pace, Mercedes-powered Pierre Gasly took pole, ahead of George Russell and Oscar Piastri.

Leclerc crashed out on the second lap, while his teammate struggled home in sixth.

"I don't want to give details, but when you have a lack of pure power, then you start to play with deployment to try to compensate in one straight line," explained Fred Vasseur post-race.

"But if you deploy more somewhere, for sure you will deploy less somewhere else and then you are going in the wrong spiral to try to play with this when you are fighting," he added.

"Honestly, it's not about deployment," he insisted. "I think deployment was okay-ish, even McLaren, they were playing a little bit Friday and Saturday morning. In the end, we are missing pure power."

However, the Frenchman insists that the nature of the Monza circuit exaggerated the issue.

"The reality is that if you are missing X in Zandvoort, you are two or three tenths down. If you are missing X minus - I'm using letters because you will try to extrapolate - if you are missing a bit less than X in Monza, the delta with the Merc is two times bigger."

Keen to make clear that ADUO is not an instant fix for those manufacturers that are struggling, the Frenchman believes that the upgrades will pay off in time.

"On the engine, the process is mega long because the lead time of the parts is long and the cost cap is not easy," he explained. "You have to produce the engine for the season. You are already a bit like this and if you want to start to do the development, you have to produce a new batch of engines, and it's tricky.

"We were not expecting to recover with ADUO 1 or ADUO 2," he admitted. "We are doing small steps, but what you have to keep in mind is that if you make a small step on the engine, even if you make a couple of horsepower, it's a good step on the grid.

"That means that now we will have a new engine next year," he continued. "For sure, the target is to catch up, to catch up as soon as possible, but I was not expecting that in two months we will recover the delta with Mercedes."

Like Ferrari, Honda and Audi are allowed two upgrades, while Mercedes is allowed one. Red Bull, the clear pace-setters - despite not having won a race and Mercedes-powered cars claiming all 13 pole positions thus far - are not allowed any.

Interestingly, at Haas, along with a raft of upgrades to his car, Oliver Bearman was given the latest Ferrari power unit, while teammate Esteban Ocon had the old package.

"It's a much smaller step than what the aero upgrade was," said the British driver of the latest Ferrari unit. "Of course, there's a bit more in this track, but in terms of a season average, it wouldn't have been enough to get us out of the fight for Q1, to be honest, if you put that engine on us in Zandvoort. I don't think it was a game changer.

"Of course, more power is always nice," he added, "but you've read the news about how much it is. It's definitely beneficial, but the biggest step was the aero upgrade, which was more than twice or three times the amount of power we got from the engine."