The second-seeded Djokovic converted his only two break points of the match, then finished it off with a crosscourt forehand winner Tuesday.
Djokovic essentially gave back a point in the second set. A groundstroke from Robredo clipped the baseline and Djokovic couldn't handle it, but the ball was erroneously called out. After a review showed the ball was in, the point was ordered to be replayed.
Djokovic shouted "It's OK, it's OK" as the fans at Key Biscayne applauded his sportsmanship.
The start of play was delayed nearly an hour by rain. Andy Murray, Serena Williams, Roger Federer and Rafael Nadal were all scheduled for matches later in the day.