A dominant Lewis Hamilton is refusing to get carried away and believe a second Formula One title is his for the taking this season.

After a hat trick of successive wins for the first time in his F1 career, Hamilton is favourite to make it four in a row after emerging quickest in practice for tomorrow's Spanish Grand Prix.

Hamilton was almost half a second quicker than Mercedes team-mate Nico Rosberg at Barcelona's Circuit de Catalunya, with the rest virtually nowhere.

Even though rival teams are boasting major upgrade packages to their cars, Mercedes still appear in a class of their own.

At this early stage it appears inconceivable Hamilton or Rosberg will not win the title, but the Briton is not resting on his laurels.

He said: "We're only 20% of the way into the season. We've a long, long way to go before we see the light at the end of the tunnel. Renault may all of a sudden pick up some pace with their engine, others might improve their cars."

If Hamilton can make it four consecutive victories with a maiden win in Barcelona, he will then have F1 history on his side. Any driver who has won four races in a row in one season - and it has happened on 19 previous occasions - has gone on to win the title that year.

Hamilton said: "I've not really thought about it, just as I didn't think about the opportunity to win three [in a row]."