World number two Rafael Nadal starts with win at Barcelona Open . Reigning champion enjoys 30th straight victory in the tournament . Former world number one Roger Federer wins his first title of the year against Juan Martin Del Potro. German Mona Barthel watched Ivanovic win French Open whilst at school .
World number two Rafael Nadal starts with win at Barcelona Open . Reigning champion enjoys 30th straight victory in the tournament . Former world number one Ana Ivanovic loses to qualifier in Stuttgart . German Mona Barthel watched Ivanovic win French Open whilst at school .