Red Bull F1 team promises major chassis 'revamp' for Spanish GP

Despite predictions that the greater focus on aerodynamics under the 2017 rules would give Red Bull a chance to return to its championship-winning form of 2010-14, the team has begun the season a clear third-best.

Max Verstappen's third place in China is its only podium from the opening three grands prix, and it is already 55 points adrift of constructors' championship leader Ferrari.

Red Bull motorsport consultant Helmut Marko said blame for that form partly lay with engine supplier Renault's early reliability problems - which led to it initially reverting to its 2016 MGU-K - but admitted the chassis was also deficient.

"We have two problems: Renault had some reliability issues, which have slowed them down in the development; and we didn't deliver the chassis that we should have done," Marko told the official F1 website.

"But we are working day and night to pick up our shortcomings.

"We are pretty optimistic that we will make a significant step forward in Barcelona where a big change of parts is coming."

Asked to confirm if the update would be "massive", Marko replied: "Yes, the chassis will be 'revamped' in Barcelona and Renault is planning something for Montreal."

Red Bull team principal Christian Horner said in Bahrain last weekend that the squad still had faith in the "different" core concept of its design and was confident its potential would be unlocked with development.

The Sakhir race was the most competitive of Red Bull's season so far, with both Verstappen and Daniel Ricciardo running with the leaders early on.

Verstappen, who retired early with a brake failure, felt the hot temperatures in Bahrain had helped.

"The car was performing really well, especially in the race," said Verstappen.

"I was trying to push up to Lewis [Hamilton, in third] and Lewis was pushing up to the guys in front and it seemed to work pretty well for us.

"The track was pretty hard on the tyres and that seems to suit our car really well."

Verstappen's pacesetting performance in Saturday free practice, held in even higher temperatures in daytime, underlined Red Bull's strength in such conditions.

But there are question marks over its soft-tyre pace.

Ricciardo believes the fact Williams driver Felipe Massa was able to overtake him after the safety car restart and stay ahead for 10 laps was telling.

"When you look at a Mercedes or a Ferrari, we could just say they are able to get their tyres working well because they have got a lot more downforce and they are generating more [temperature] through the tyre," said Ricciardo.

"But the fact that Felipe passed me and pulled away in those first few laps is probably a bit of a sign for us."