Novak Djokovic celebrated his 37th birthday on Wednesday with a much-needed win as he gears up for his French Open title defence, progressing to the Geneva quarter-finals.

The world number one downed Germany's Yannick Hanfmann 6-3, 6-3 in the second round at the Parc des Eaux-Vives grounds.

Djokovic took a wild card to play in Geneva in a bid to rescue an alarming dip in form ahead of next week's French Open, the second Grand Slam of the year.

The crowd sang "Happy Birthday" to Djokovic as a cake with candles was brought out onto the court following his win.

He lifted the cake and showed it off to the crowd, having a nibble before offering some to the ball boys and girls. (AFP)