Chelsea attacker Eden Hazard has been forced to withdraw from Belgium's squad for the World Cup qualifier against Greece and the friendly versus Russia due to a calf injury.
The winger suffered the problem during a training session ahead of the Premier League encounter with Stoke and missed the 2-1 victory.
"Eden's absence is obviously a big blow, but it will be interesting to see how we deal with it," Martinez said at a news conference.
"Eden suffered a calf injury the day before the game against Stoke. It does not appear to be too bad based on the information Chelsea gave us. Eden came to Belgium on Monday, but he will not remain with the group.
"Of course, this will be a disappointment for him. He is a very professional captain. But injuries are part of the game. A big test awaits without Eden."
