Rosberg sends birthday best to 'old' rival Hamilton

LONDON (Reuters) - Formula One champion Lewis Hamilton celebrated his 30th birthday on Wednesday, with Mercedes team mate Nico Rosberg hoping his 'old' opponent will be easier to beat this season. "30!! Have a great party! This day is good for me. You are old now, so hopefully it will be easier for me this year," the 29-year-old German, runner-up to Hamilton in a dominant championship for the team, told his rival on Twitter. Hamilton won 11 grands prix in 2014 to Rosberg's five to take his second title and become Britain's first multiple champion since Jackie Stewart took the second of his three crowns in 1971. The man who made his Formula One debut with McLaren in 2007, and won his first championship the following year, has now won more races than any other British driver and starts the new season in March as favorite to triumph again. Hamilton and Rosberg have been friends since their early teens, when they were karting team mates, but their relationship was severely tested in the heat of battle last year. "It is hard to believe that 30 years have passed. So many great memories," said the Briton on facebook, posting a picture of himself as a baby and thanking his parents. 'I have lived my life to fullest and am grateful for the years I've had." (Reporting by Alan Baldwin, editing by Ken Ferris)