Djokovic 'shocked' & 'overwhelmed' by Nadal retirement as great tennis era ends

24-time Grand Slam winner Novak Djokovic says he is "shocked" and "overwhelmed" by the news that Rafa Nadal will retire at the end of the season. He also marks it as an end of a great era in tennis saying "a part of me left with them" as Nadal follows Andy Murray and Roger Federer in retiring from the sport.