BARCELONA, Spain -- After four consecutive one-two victories for Mercedes in the first four races, a lot rests on this weekend's Spanish Grand Prix injecting some excitement into the season. Ferrari has shown promise throughout the opening four races and, arguably, had the quicker car in two of the four. However, from the raw numbers we saw during Friday practice, there is little hope Spain will be the turnaround Ferrari was hoping for.
On single-lap pace, Ferrari had a 0.3s deficit to Mercedes, and the gap extended to 0.4s to 0.5s on like-for-like long runs. The Mercedes, at least in Valtteri Bottas' hands, looked like the more drivable car and, after a series of Friday practice sessions when Ferrari appeared to have the edge, Mercedes heads into qualifying day as the clear favourite.
Of course, there are all the usual caveats that come with any Friday practice session. Ferrari looked to hold a significant advantage in Baku, yet it was Mercedes that locked out the front row and took a one-two victory. But in terms of finding a setup, Barcelona is much more familiar ground and there are far fewer excuses for starting on the wrong foot with setup. Instead, teams usually come here knowing small margins will make the difference, making Mercedes' sizable advantage all the more concerning for Ferrari.
The only big difference this weekend compared with others is the number of upgrades on the cars. While those updates are all intended to bring performance, they can also change the balance of the car and the requirements from the setup. So, could Friday's woes be solved with a better understanding of the data and some setup tweaks overnight?
"At the moment, the balance is a bit out of the perfect balance," Ferrari driver Charles Leclerc said. "But this is a thing that can be fixed and also things that are not un-normal when you are putting new parts on the car. It's normal that it takes some time to understand them and then once we put all of them together the balance will be good and we will see how we perform."
But drill a bit deeper into where Ferrari is losing time and it's a familiar picture that emerges. The Circuit de Catalunya is full of high-speed corners in the opening two sectors while the final sector is defined by a low-speed chicane. Ferrari has struggled relative to Mercedes in slow and medium-speed corners on a number of occasions this year -- and did so in testing -- so it seems the vices of the SF90 have not been removed by the upgrades.
"It's not the first time this year that we are losing in these sorts of corners," Vettel said after the session. "If it was easy, we would just fix it, but currently we are all working very hard and trying still to just understand why we are losing out in these types of corners -- sometimes more than other times.
"It's not really traction, it's overall grip in slow corners. Obviously slow corners can be nasty because if you don't have a lot of grip you lose quite a lot of time."
At Mercedes, the difference the upgrades made was more obvious in lap time, although Hamilton complained of a different balance. Bottas was much happier -- something that was visible from the car's behaviour on track -- and believes Mercedes has made a useful step from the last race two weeks ago.
"It was an interesting day, as always, when you bring new parts to the car and you try to feel if they bring the performance they should," he said. "But it really felt good today -- the cornering performance has improved, so that's good, and the overall level of downforce from when we were last here in testing.
"I can't put a number on it, but a decent step in terms of upgrades and performance is how it is looking. But we will see tomorrow in qualifying when Ferrari turns its new power unit up."
Hamilton, meanwhile, revealed why Mercedes still has some cause for concern when it comes to engine power and Saturday afternoon.
"Ferrari is always gaining something like 0.4s on the straights," he said. "I don't know if that's because they are up on power, but for us we have work to do on the balance. Still it's really positive for us to be up there."
On the long runs, the Mercedes advantage appeared to increase. That might be down to Ferrari getting less of an advantage from its engine in race trim, but Mercedes held the edge on all three compounds. Of the two Mercedes drivers, Hamilton put in the more impressive soft-tyre run, but, as with the one-lap pace, there wasn't much to choose between the two teammates.
At this stage, Ferrari needs to find a solution to bring its cars closer to Mercedes in the final sector of the lap while relying on its updated engine to eclipse the rest of the gap on the straights. If the Ferraris can start ahead, they have the pace to win from the front, but doing so from the second row with tyre strategy alone will prove mighty difficult.
Red Bull struggled in both sessions and was not helped by an oil leak on Max Verstappen's car in FP1. The problem occurred on the Spec 1 engine the team has designated for Friday practice, and it planned to swap it for its Spec 2 engine (introduced at the last round in Baku) overnight anyway. Over a single lap, Verstappen was 0.7s off Bottas and -- worryingly for Red Bull, which usually closes the gap in the race -- had a similar deficit on long runs.
On the face of it, Haas looks as if it has the potential to finally deliver on its preseason promise and mix it with Red Bull. Romain Grosjean split Verstappen and Pierre Gasly and was the only Haas driver running the team's upgrade (Magnussen will get it tomorrow after running the old spec in order to get a comparison on Friday). Long-run pace was less impressive, however, with Grosjean 0.8s off the pace of Verstappen when both cars hit the track on soft tyres and heavy fuel.
Renault, and to a lesser extent McLaren, looked like the pick of the bunch from the midfield teams on long runs. Daniel Ricciardo had a hugely impressive 15-lap run on the medium compound tyres that was a match for Vettel's similar 17-lap run on the same compound. Ricciardo was the only one of the Renault-supplied drivers using the French manufacturer's updated power unit, which is designed to improve reliability to allow drivers to run in higher engine modes for longer. The other three drivers (Nico Hulkenberg, Lando Norris and Carlos Sainz) will receive the update on Saturday.