Bottas must win again quickly to avoid Mercedes demotion - Massa

Bottas's 2014-16 Williams team-mate Massa believes Sebastian Vettel is already clearly established as the sole championship contender at Ferrari, and that this could force Mercedes to put its resources behind Hamilton unless Bottas makes an immediate case for his own title potential.

Massa, who ended up supporting Kimi Raikkonen's championship bid when they were team-mates at Ferrari in 2007, is sure Bottas is capable of matching Hamilton after his Russian Grand Prix win.

"I don't see that it's impossible for Valtteri to fight with him," said Massa.

"To be able to fight with Lewis, now is the right time.

"If he's after the championship, now he has to improve.

"If you see Kimi, he will work for Sebastian for the whole championship. It's clear.

"If you have another team that is fighting for the championship and you have a driver that is more than 20 points behind, he will need to do the same. So now is the time [for Bottas].

"If he wants to fight with Lewis he needs to win another race here, he needs to score more points than Lewis now.

"Then the team cannot do anything."

Though Hamilton was outpaced by Bottas throughout the Russian GP weekend, the Briton said ahead of this weekend's Spanish round that he now understood the "bunch of small things that all added up in one pot" and caused him to struggle last time.

But Bottas believes he learned from his advantage in Russia too.

"In F1 if you're quick in many cases it's all about small things," he said.

"I've always felt comfortable in Sochi, but it's not down just to that.

"I feel I've been progressing race by race, I felt Russia was my best weekend so far this year in terms of my own performance, no matter about the track.

"I've looked into every single thing from Russia - what I can do better and what I did good and so on - and I do understand all of the points why there was a difference.

"I'll try to keep good momentum out of that."

Hamilton and Bottas began the Barcelona weekend first and second in Friday morning practice, with Hamilton 0.029 seconds ahead.