But 2015 was a pivotal year for Djokovic .
He won 11 titles overall , including six Masters 1000 crowns and three Grand Slam championships , falling just short of completing the Calendar Grand Slam , losing to Stan Wawrinka in the French Open finals back in May .
2015 was a pivotal year for Djokovic .
He won 11 titles overall , including six Masters 1000 crowns and three Grand Slam championships , falling just short of completing the Calendar Grand Slam , losing to Stan Wawrinka in the French Open finals back in May .