Former world champion Damon Hill believes there is more to come from Lewis Hamilton, and that the British driver could be unbeatable this season.
The 53-year-old's comments come following Hamilton's fourth consecutive race win of the season in Spain, which has seen him move top of the drivers' championship.
Hill said: "Up until this season, it always looked like Lewis's focus could go at any time, but he now seems to have the demeanour of someone who is totally content.
"I do wonder if he is just cruising. I think he has another gear. He is so focused on the job, I think he will be almost impossible to beat."
Hamilton and Mercedes team-mate Nico Rosberg have enjoyed a highly competitive rivalry in the opening five races, with the Brit getting the better of the German in all but one race so far.
And the only time Rosberg has out-performed Hamilton was in the season opener at Australia, when the latter was forced to retire due to engine trouble. Since then, it's been plain sailing.
The next race will take place on the streets of Monte Carlo, with the Monaco Grand Prix scheduled for the 23-25th of May. It is widely expected that Mercedes will continue their dominance again.
Rosberg has had chances to beat his team-mate - who has been a rival since their childhood karting days - so far this season, but has let them all slip through his fingers.
But on the streets of Monte Carlo, a circuit Rosberg enjoys, grew up near and won at last year, he needs to outperform Hamilton to keep the title race alive through the summer months.
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