Lewis Hamilton plans to look back at his emphatic victory in Spain as the turning point that fired him to a fifth Formula One world championship.

While there was more than a hint of fortune about the opening victory of his title defence in Azerbaijan a fortnight ago, there could be no denying Hamilton's win here at Barcelona's Circuit de Catalunya.

The 33-year-old British driver was in a class of his own as he galloped to a 21-second triumph – lapping the field up to fifth – while his main championship rival Sebastian Vettel faltered to only fourth place. Hamilton's championship lead now stands at 17 points.

Arriving in Spain, Ferrari boasted the grid's most complete package, but Hamilton's display was a return to the Mercedes of old with Valtteri Bottas following his team-mate home to secure the world champions their first one-two finish of the campaign.

Hamilton conceded that he will head to the next round in Monaco with caution rather than in expectation following his poor display at the principality last year, but the 64th win of his career will, for the first time this term, provide him with optimism that he can outdo Vettel in their tug of war for glory.

"I would like to hope that this race could be part of a turning point," Hamilton said. "I said that I wanted to come here and win the way that I won, and when I came across the line I was just happy that I did as I planned to.

"The team have been working very hard to understand the tyres and how the car works, so I think it all came together this weekend.

"We definitely go to Monaco on a high note, but we know that we still have a lot of work to do. That said, I will sleep like a baby tonight."

Hamilton should have kick-started his season with a victory at the opening rubber in Australia before a strategy mix-up by his Mercedes team gifted Vettel the win.

He was at his very best in Melbourne but was then, by his own admission, off-colour in Bahrain, China and even Baku despite his victory.

Mercedes boss Toto Wolff admitted Hamilton's confidence had taken a knock.

"The best ones are very sensitive and fragile and that is something we know and he knows," Wolff said.

"He was solidly in the lead in Melbourne and suddenly he was behind the Ferrari. It is difficult to cope with and in the following races we struggled. But having such a good weekend here, and winning by a solid margin, is very important for his confidence."

After edging out Bottas for pole, Hamilton roared off the line to retain his lead on the 200mph charge to the opening bend, while Vettel got the jump on Bottas after a gutsy move around the outside of the Finn.

The leading cars navigated the opening metres without drama before the error-prone Romain Grosjean, once labelled a "first-lap nutcase" by Mark Webber, lived up to that title by sparking a huge crash after he lost control of his Haas at Turn 3 and slid back across the track in a cloud of tyre smoke.

Toro Rosso's Pierre Gasly and Renault's Nico Hulkenberg were unsighted and could do little to avoid the Frenchman. Grosjean was punished with a three-place grid penalty for the next round in Monaco.

Out came the safety car with Hamilton then executing a masterful restart to leave Vettel for dust before establishing a comfortable cushion over his rival.

Vettel was the first of the leaders to stop for fresh tyres, but was the only one who needed to stop again, which cost him two places.

He could do nothing to fight his way back past Max Verstappen, who despite banging into the back of Lance Stroll's Williams, took the final spot on the podium.