Gareth Southgate says he will not discard Kyle Walker because of his red card in Saturday’s 1-0 Nations League win over Iceland but he will “hammer home” the importance of discipline to each of his players as he prepares for Tuesday’s game in Denmark and the challenges beyond. The manager has an eye on next summer’s European Championship finals and he is aware of how sendings-off have damaged England at major tournaments in the past. He was in the England team when David Beckham was dismissed in the 1998 World Cup last-16 exit against Argentina while Wayne Rooney’s red card was costly in the quarter-final defeat against Portugal in 2006. Southgate made the point about the dangers of indiscipline to his players when he was the England Under-21s manager and, after Walker became the first player to be sent off during his four years in charge of the senior team, he said his squad had to be similarly mindful. England beat Iceland 1-0 thanks to Raheem Sterling’s 90th-minute penalty and an even later miss from the spot by the Iceland midfielder Birkir Bjarnason. But Walker’s dismissal in the 70th minute for a reckless lunge that brought a second yellow card had put England under pressure and Southgate knows his team can ill-afford that kind of misjudgment in a major game. He said he would not judge Walker on one moment but when he highlighted the fierce competition for places at full-back, it sounded as if Walker was on thin ice. “Kyle knows he made an error that shouldn’t have happened and he’s been very open and honest about holding his hands up to that,” Southgate said. “He’s still a very experienced player. There is competition for places. Kieran Trippier did an excellent job at left-back. But I am not going to rule Kyle out in the long term on that one moment. “We were very conscious with the under-21s to talk to the team about discipline because we’ve learned what had happened with the seniors in the past. The same applies now. “It’s the first time we’ve had a red card in my four years and it makes the game so difficult. It could have cost us the game. We got away with it but it’s something all of the players … it’s a good way to learn, to still win the game, but to have to hammer those points home because it’s critical.” James Ward-Prowse, the Southampton midfielder who made his full England debut against Iceland, has said that he has embraced some of the game’s darker arts under his club manager, Ralph Hasenhüttl, and they are “something which we can all take forward, for sure”. Ward-Prowse stood on the penalty spot before Bjarnason blazed his kick off target, although he denied digging up the turf with his boots. “It was more a delaying tactic, just for everyone to get their heads together and prepare for the penalty,” Ward-Prowse said. “There are certain scenarios in a game and you have to take yourself out of the situation and see what is best at that time. It is something that we at club level have employed. We maybe had the reputation of being a bit too nice and we have maybe had to show a bit more aggression and a bit of that darker side. It’s an important factor in the modern game.”