Lewis Hamilton believes Mercedes teammate Valtteri Bottas will be a genuine threat in the title race this year.

Bottas took the first win of his Formula One career at the Russian Grand Prix two weeks ago and drew within 10 points of Hamilton in the drivers' standings, who in turn is 13 points shy of championship leader Sebastian Vettel. Just two weeks earlier, Bottas had been asked to move aside for Hamilton at the Bahrain Grand Prix but Hamilton has no doubt his teammate can mount a title challenge this season.

"Of course he's a credible competitor [for the title], he was when he joined," Hamilton said. "I think it was many of you [in the media] and perhaps people who are fans, whatever, came with preconceived ideas of how he was going to perform and he's proved everyone wrong.

"So fair play to him and he's going to remain a competitor through the rest of the year so the fight will go on and we've stated our relationship with a really great foundation I think, a respectful foundation and I think that will continue."

Hamilton finished 36 seconds off the pace of Bottas in Russia after struggling to get the most from his tyres in the race. However, he believes the team has since found a fix to prevent his issues reoccurring in Spain.

"It was just a bunch of small things all added up in one pot. Nothing in particular, no single one thing that was bigger than another, that just led us in slightly the wrong direction. Should be better this weekend.

"It's a tyre issue in the sense that the tyre's working range is quite small, so yeah, the whole weekend I generally wasn't in the right window with it."