8 May 2014 Last updated at 21:22

Lewis Hamilton: Mercedes still pushing to improve

Lewis Hamilton says that if other teams are "throwing the kitchen sink" in an attempt to catch Mercedes, his team will "throw the bathtub" to stay ahead.

Speaking ahead of the Spanish Grand Prix, Hamilton believes other teams will have to make a "pretty big step" while Ferrari's Fernando Alonso and Red Bull's Sebastian Vettel are also under no illusion as to how far they are behind the Silver Arrows.

On the other side of the garage, Hamilton's team-mate Nico Rosberg says he needs the momentum to swing back his way if he is to build his championship lead over Hamilton.

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