Six-time champion Novak Djokovic's hopes of turning around his season at the Miami Open have ended in the second round when he was defeated 6-3 6-4 by Frenchman Benoit Paire.

The loss snapped a 16-match winning streak in the tournament for the ninth-seeded Serb.

He won the tournament in 2014, 2015 and 2016 but missed last year's event with the elbow injury that plagued him for much of 2017.

The defeat also ended a streak of 21 consecutive victories over players from France for the former world number one.

"I'm trying, but it's not working," Djokovic told the Miami Herald. "That's all it is. I mean, obviously I'm not feeling great when I'm playing this way.

"Of course, I want to be able to play as well as I want to play. Just it's impossible at the moment. That's all."

Meanwhile, Juan Martin del Potro survived a battle with Robin Haase to capture his 12th consecutive win, 6-4 5-7 6-2.

Del Potro, who defeated world number one Roger Federer to win the Indian Wells Masters last week, needed two hours and nine minutes to advance.

Second seeded Croatian Marin Cilic moved into the third round with a 7-5 6-3 triumph over Frenchman Pierre-Hugues Herbert and third seed Grigor Dimitrov rallied from a set down to beat German Maximilian Marterer 4-6 6-2 6-1.

David Goffin was unsuccessful in his return from an eye injury, the seventh seeded Belgian falling to Portugal's Joao Sousa 6-0 6-1.

American wild card Michael Mmoh produced another surprise, upsetting 12th seeded Roberto Bautista Agut 7-6 (7-4) 2-6 6-4 in two hours, 43 minutes.

Diego Schwartzman and Milos Raonic also moved on, while Australian Davis Cup teammates Matt Ebden and John Millman won't be joining countryman Thanasi Kokkinakis in the third round.

Japanese star Kei Nishikori clawed back from from 2-5 in the first set to beat Millman 7-6 (7-4) 4-6 6-3.

Ebden was beaten by rising Korean Hyeon Chung 6-3 7-5.