England manager Gareth Southgate fears his players could face more racial abuse in Bulgaria after an away supporter allegedly targeted Raheem Sterling when the teams met at Wembley last weekend.
The Football Association has said an individual was ejected from the national stadium for "discriminatory abuse" during Saturday's 4-0 Euro 2020 qualifying victory over Bulgaria.
Bulgarian supporters made monkey chants at England's black players when the side last visited Sofia in 2011, prompting UEFA to fine the Bulgarian Football Union 40,000 euros ($44,000).
"It is a concern," Southgate, who plans to consult his players before the Oct. 14 encounter, told British media.
"We're aware that there is history there and we want to make sure that we're all prepared for what might happen and how we want to respond.
"We didn't think it was right to do it this month because it's too far away from the games, but we have to hope. We're not confident that we'll go there and nothing will happen."
UEFA has ordered the Bulgarian Football Union to partially close the Vasil Levski national stadium for England's visit after supporters were found guilty of racist behaviour in matches earlier this year.
Southgate also expressed concern over the behaviour of England fans on upcoming trips to Czech Republic and Bulgaria, after violence involving some supporters overshadowed the recent Nations League finals in Portugal.
"I'm afraid that it is a societal issue of people with alcohol unable to control themselves," he said. "But we certainly don't want to be taking that abroad and that being a representation of our country."
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