England manager Gareth Southgate urged James Maddison to become a "low-maintenance" player for the national team.
The uncapped Leicester City star, 22, was named in England's squad for this month's Euro 2020 qualifiers against Montenegro and Kosovo.
Maddison, who has three goals and two assists in the Premier League this season, was pictured in a casino after pulling out of the last squad due to illness.
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Southgate said the attacker needed to remain focused as he tries to cement a spot in the England setup.
"It's not a good situation for a player when we're talking about him in Sofia, and talking about him here and he's yet to get on the pitch for us," he told UK newspapers.