LEWIS Hamilton believes Valtteri Bottas has proved his doubters wrong and insists the Finnish driver must be considered a real threat for this year's three-way title race.

Bottas held off the challenge from championship leader Sebastian Vettel at the Russian Grand Prix a fortnight ago to claim his first victory in the sport and move to within ten points of Hamilton.

The Briton arrived at the Circuit de Catalunya, on the outskirts of Barcelona, for the start of the European season himself 13 points behind Vettel after a mysteriously dour weekend at the Sochi Autodrom.

Bottas was expected to be no more than an able deputy to Hamilton at Mercedes after he was chosen to replace Nico Rosberg – but he has outqualified his team-mate at two grands prix in succession and finished 36 seconds clear of the British driver at the last round.

"I said from the beginning of the season that Valtteri was in competition, so it is no surprise that he would eventually get a win," said Hamilton.

"Of course he is a credible competitor. He was when he joined. Many of you, and perhaps the fans too, came with preconceived ideas of how he was going to perform and he has proved everybody wrong.

"Fair play to him. He is going to remain a competitor throughout the rest of the year, so the fight will go on. We have started our relationship with a respectable foundation and I think that will continue."

Hamilton was a distant fourth in Russia and after the race appeared at a loss to explain why he was so slow at a circuit at which he often excels.

Yet his Mercedes team have worked round the clock in a bid to ensure Hamilton is back on the pace for the fifth round of the championship – and while his boss Toto Wolff warned earlier this week there would be no "magic bullets" to resolve the Briton's troubles, Hamilton is hopeful he will be back on track in Spain.

"Coming into this weekend we have a good understanding of where we went wrong on our side of the garage in Sochi," said Hamilton, who has not finished off the podium at consecutive races since 2013.

"There has been a huge amount of analysis so we have definitely grown from the experience – both having a win and a fast car – and a car that struggled in so many areas. We are better equipped now.

"I can't say if it is going to be better this weekend, I assume it will be, but there are lots of different challenges this weekend. We will be doing a lot of work Friday to get the car in the right place."

For Bottas, he was forced to put his victory celebrations on hold by 24 hours as he headed straight from Russia to Hungary to complete a demonstration run on the streets of Budapest.

But after a night out in Hungary's capital, the former Williams driver says he is now ready to build on the opening win of his career.

Bottas said: "It took some time to properly realise I won the race. It is quite nice but after a few days, it is done.

"There are good vibes – but then there is always the next race to focus on. If you stay in the clouds too long then you fall very hard back down again."