Lewis Hamilton: Understanding of car worse than a year ago

All eyes on Alonso, Red Bull in Spain (2:45)

Nate Saunders and Laurence Edmondson discuss the weekend's biggest talking points ahead of the Spanish Grand Prix. (2:45)

BARCELONA, Spain -- Lewis Hamilton is not sure when he will be unable to unlock the true potential of his Mercedes after admitting the team's understanding of the car is not as good as it was a year ago.

Despite holding a four-point lead in the championship and scoring his first victory of the season at the Azerbaijan Grand Prix two weeks ago, Hamilton has struggled to hit his stride this year. Difficulties keeping Pirelli's new tyre compounds in the optimum operating window has seen Hamilton struggle for performance ever since his strong performance at the Australian Grand Prix, and he has twice been outqualified by teammate Valtteri Bottas in the first four races.

Mercedes hopes updates to the front wing and floor of the W09 will help improve its performance at this weekend's Spanish Grand Prix, but Hamilton says there is no way of knowing if they will help with his tyre issues.

"I have no idea how this weekend is going to go -- last year here I had no idea how we were going to go," he said. "I would say we were a little bit more confident last year in the hope of starting on the right foot because we understood the car a little bit better already by this point. There's still a lot of unknowns into this season right now and we're still learning and hoping...

"The tyres are really the biggest contributor at the moment to the struggles that we've had. So I'm hoping that this weekend we don't have those issues, but I have no idea. They've just changed the tyres again for the blistering issues we had in testing [by reducing the tread depth to combat overheating] so it could go from a two-stop to a one-stop or maybe a three-stop. I have no idea what it's going to do. But I do hope it's not a one-stop because that's not very exciting."

Asked if he believed rivals Ferrari have the faster car at the moment, Hamilton added: "It is. I believe so.

"I'm pushing with this great team to turn this car into the best car. We're talking mini percentages. At the tracks so far the Ferraris ... it seems to have worked quite well for them and their car has been quite strong. I anticipate that they'll be very strong here this weekend.

"It's really more about unlocking... It's really hard to say who has the best car because up until now Ferrari has had the best. But maybe it's about unlocking the potential of our car, so maybe it's about the potential of having the mindset of the glass being half full."