Chantilly - England's players will find it "devastating" if they are thrown out of Euro 2016 due to fan violence, midfielder Adam Lallana said on Tuesday.
European governing body UEFA has formally threatened to expel Russia after stadium violence in Marseille and put England on notice over its fans' behaviour.
"It would be devastating," Lallana told a press conference when asked about the expulsion threat.
"Our message is for everyone to be safe and sensible, enjoy the day, enjoy the match, and be respectful when we're playing."
England play neighbours Wales in the northern French city of Lens on Thursday (June 16). Their supporters have been advised to stay in nearby Lille, where Russia play Slovakia on Wednesday (June 15).
The England-Wales game is one of five "high-risk" fixtures identified by tournament organisers due to fan violence concerns.
Football Association chairman Greg Dyke said in a letter to UEFA that he has "serious concerns" about security in Lille.
England manager Roy Hodgson and captain Wayne Rooney have both called for fans to behave and urged supporters without tickets not to travel to Lens or Lille.
Russian supporters charged England fans at the end of the teams' 1-1 draw at Marseille's Stade Velodrome.
England goalkeeper Joe Hart could be seen telling supporters to "stay safe", while Rebekah Vardy, wife of striker Jamie, wrote on Twitter that the violence prior to the game had been "horrific".
FA spokesman Mark Whittle said a private website had been set up to allow family and friends of the players to access information about security in France.
"The FA has liaised with the players' families and provided advice for them, on an as-and-when basis," he said.
"We've run a private website for family members and friends that players can access to receive up-to-date information.
"We have staff in place from an operational and security point. If there are any concerns, family members can contact them and we give them advice."
Asked if the players had talked about what happened in Marseille, Liverpool player Lallana replied: "A little bit's been discussed.
"It's not nice to see. We've just got to hope the security is there and we trust everyone to do their job.
"I've got friends and family coming to the game (against Wales). I trust everyone to be sensible and safe.
"Obviously it's a big game, England against Wales. We've just got to focus on our objective, which is playing football. I'm not concerned (about safety)."