Ferrari were dominant in the Principality last year, with Sebastian Vettel leading home team mate Kimi Raikkonen for their first one-two of that campaign. Red Bull’s Daniel Ricciardo completed the podium in third.
The best-placed Mercedes was Valtteri Bottas in fourth, with Lewis Hamilton capping a challenging weekend with a disappointing seventh, having qualified down in 14th.
And while the Briton will hope to be higher this year, he reckons the advantage could swing Red Bull's way in Monaco, referencing the team's supreme pace in Barcelona's slow-speed final sector, which is often a barometer for Monte Carlo form.
“We came from the last race knowing this is going to be one of the tougher races for us,” said championship leader Hamilton. “If you look at the last race [in Barcelona] and even in testing in February and even the test the other day, the Red Bulls were particularly quick in the last sectorsector – that’s where they’re always very, very strong.
"So you can imagine that they will be incredibly quick here this weekend, which is actually a surprise on previous years, because Ferrari were very strong last year and for whatever reason, Red Bull didn’t get it together but maybe this weekend they will.
“I do anticipate it’s going to be a difficult weekend [for Mercedes] – not one that is impossible but it’s a lot closer and we may not have the pace of the others.
“But we will find out tomorrow the true pace and identity of what we arrive here with. I’m excited for the challenge. If you look at last year, there were overcuts and undercuts so anything is possible.”
Mercedes struggled to assert their authority in the opening three races before somehwat fortuitously taking victory in Azerbaijan. But in Spain, they appeared to be back to their dominant best. Hamilton feels the team still have plenty of work to do, but they are making progress, which bodes well for the coming races.
“I feel with the last race, the whole weekend, we took a lot of information,” said Hamilton. “The whole first five races, we’ve learned a huge amount.
“We know our targets, we understand our issues. We’re working hard to address them. I think we’re working in the right direction and I feel more confident going forward. Have we rectified everything? We’ll find out.”
Mercedes turned a four-point deficit to Ferrari into a 27-point lead in the constructors' championship after their one-two in Barcelona, while Hamilton extended his lead over Vettel in the drivers standings to 17 points.