Nico Rosberg has had a cheeky dig at team-mate Lewis Hamilton after the double world champion turned 30 on Wednesday.

Hamilton's Mercedes team had been encouraging Twitter users to send in their wishes on his birthday with the hashtag #HappyBirthdayLewis. Rosberg - who is six months younger than Hamilton - then sent his own tweet which jokingly mocked Hamilton's age, saying "hopefully it will be easier for me this year" ahead of the 2015 season.

Rosberg and Hamilton had a difficult relationship as team-mates fighting for the drivers' championship last season, which culminated in the two colliding at Spa before Hamilton took the title at the last race of the season in Abu Dhabi.