David Coulthard has questioned Lewis Hamilton ’ s focus on the eve of the new Formula One campaign . Hamilton is the favourite to defend his championship with Mercedes expected to hold a clear advantage over the rest of the field when the season gets underway in Melbourne in the early hours of Sunday morning . The 30-year-old Briton has brushed shoulders with a host of A-List celebrities during the off-season as he continues to expand his profile outside of the sport . Lewis Hamilton is pictured on St Kilda beach on Thursday as he prepares to defend his Formula One title . The Briton faced the media in the first pre-race press conference of the year ahead of the Australian GP . He is also close to signing a new deal with Mercedes which will see him earn a considerable amount more than the current £20million-a-year contract he signed after leaving McLaren in 2012 . Meanwhile , his private life has also been the subject of much discussion following the break-up of his relationship with long-term girlfriend Nicole Scherzinger , the American popstar who was in Abu Dhabi to celebrate his second world championship last year . ‘ Lewis appears to be going through a transition in his off-track life , ’ said Coulthard , a 13-time race winner . ‘ I see he is negotiating his own contract , doing music in the future and has split up with Nicole , and all of these things have an influence on your life which may be a positive or negative . ‘ It will be interesting to see now that he has won two world titles , is a wealthy champion , and got lots of opportunities , whether the absolute focus is still on the job. ’ Hamilton signs autographs for fans at the Albert Park Circuit . He starts the season as championship favourite . David Coulthard , pictured on Thursday , believes Nico Rosberg will return stronger this season . Rosberg will renew his title battle with Hamilton . Hamilton and team-mate Nico Rosberg are set to go toe-to-toe for the world championship once more after the dominant Mercedes pair won 16 of the 19 races last season during a frenetic campaign . Hamilton clinched the title in dramatic circumstances at the season finale in Abu Dhabi with his 11th victory of the year . But Coulthard expects the German , who tasted victory just once after his collision with Hamilton at the Belgian Grand Prix in August , to return stronger this term . ‘ Nico now has the experience of battling for a world championship , ' added Coulthard . 'He went into last year with a good car , everything was going great , then he had the collision in Spa , his team told him he was a bad boy , and he was getting booed by the fans . 'There were so many first-life experiences for him and a lot of things he had to go through . ' I think he will be stronger . He is settled in his life , he is married and he has got a baby coming later in the year. ’ The F1 season kicks off with the Australian GP on Sunday 15 March . Watch highlights on BBC One at 13.15 , listen live on Radio 5 live and follow all the action on the BBC Sport website .
Lewis Hamilton will begin Sunday as favourite to defend his crown . But David Coulthard has questioned his focus ahead of the 2015 campaign . Hamilton has been in-demand away from the circuit over the winter and he is also in the closing stages of finalising a big-money deal with Mercedes . The campaign gets underway on the new season when Melbourne plays hosts to the sason-opening Australian Grand Prix . CLICK HERE for all the latest F1 news .