BBC Sport - 'Lewis Hamilton and Nico Rosberg rivalry will be challenging'
'Mercedes rivalry will be challenging'
- From the section Formula 1
Mercedes Executive Director Toto Wolff thinks that the rivalry between his drivers Lewis Hamilton and Nico Rosberg will be "challenging" again this season.
Hamilton eventually won the 2014 Championship after a series of racing incidents with his team-mate Rosberg.
Mercedes are topping the timesheets in the winter testing so far and are looking strong once again heading into the 2015 season, which begins in Australia on 13-15 March.
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