The playmaker sustained the injury in training with Belgium on Sunday.

No timeframe has been put on the injury -- although he will miss Belgium's international against the Czech Republic on Monday and a World Cup qualifying match in Estonia on Friday.

However, it may impact on Chelsea, as well -- for whom Hazard was back to his best last season as they won the Premier League under Antonio Conte.

The 2017-18 campaign starts in less than 10 weeks on August 12 -- but three weeks before that there are preseason games against Arsenal, Bayern Munich and Inter Milan in Singapore from July 22-29, then the Community Shield against the Gunners on August 6.

Belgium currently sit first in Group H with 13 points from five games. They hold a two-point lead over second-placed Greece, with Bosnia-Herzegovina in third on 10 points.

They beat Estonia 8-1 in Brussels back in November.

Hazard, who joined Chelsea from Lille exactly five years ago for a reported £32 million, said earlier in the day that he would be happy to stay at Stamford Bridge -- although he has not started talks about extending his stay.