Mikel and Hazard spent five years together at Chelsea and lifted the Premier League together on two occasions.
The Nigerian now plays his football in Turkey with Trabzonspor after spells for Tianjin in China and Middlesbrough back in England.
Last summer Hazard secured his dream move to Real Madrid in what was the biggest deal of the transfer window.
The Belgian has, however, struggled in Spain so far and has come under criticism from the media.
Mikel doesn't doubt Hazard's ability - he believes his former colleague is one of the best around.
"Hazard has an incredible talent," Mikel told beIN Sports in Turkey.
"Maybe not as good as [Lionel] Messi, but he can do whatever he wants with the ball at his feet."
Hazard scored 110 goals in 352 appearances for Chelsea and provided his teammates with 92 assists.
But Mikel did say that Hazard, despite his natural talent, wasn't the hardest worker in training.
"He didn’t like to train hard. While we were working he was waiting for us to finish training just standing there," he said.
"But on Sundays, he was always man of the match, it was unbelievable."
Hazard was recently criticised by Arsene Wenger for being unfit, with the former Arsenal boss suggesting he's overweight.
Hazard has one goal and three assists in seven games so far in La Liga and will be hoping to reignite his form after the international break.
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