Belgium coach Marc Wilmots could leave Eden Hazard out of the starting line-up for Tuesday's World Cup qualifier against Scotland after raising questions over the youngster's approach to defending.
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Belgium defeated Serbia 3-0 on Friday as they moved to seven points from three games, but only after overcoming a rocky start to the match in which the hosts came close to breaking the deadlock.
After the match, Wilmots had said: "Nacer Chadli and Eden Hazard had to switch positions because we were all over the place in the opening exchanges and very fortunate not to fall behind in the first seven minutes. Also, bringing on Dries Mertens for Hazard early in the second half injected fresh blood into the team."
Belgium had been 1-0 ahead at the time of Hazard's substitution, and the improved performance after his departure has led to suggestions Mertens could start against Scotland at the King Baudouin Stadium in Brussels.
Wilmots, who insists no players have an automatic place in his first XI, acknowledged that the 21-year-old Chelsea midfielder must improve his all-round game if he is to continue to start for his country.
"I spoke to him after the game," Wilmots told the Belgian media. "On Friday I had to move him away from the centre and put him out on the flank to restore the balance in the centre with Chadli, [Mousa] Dembele and [Axel] Witsel.
"Eden should know that, in football today, changing from defence to attack and from attack to defence are essential. But I support him. Step by step, we will get there."