"I wasn't aware of the conversation Danny had with his family, but everything else he talked to us about", he said. They're the tough calls.
One change to his side that Southgate confirmed on Wednesday is that Stoke City goalkeeper Jack Butland will start ahead of Everton's Jordan Pickford, who has been handed the No. 1 shirt.
Southgate said: "I don't think anybody gets to be a top player without having resilience and that is developed in different moments of your career. When the gaffer told me, I was just really pleased for Harry and he is a fantastic player".
England face Costa Rica at Elland Road on Thursday and will play a practice match in training before flying to Russian Federation on June 12, but Cahill believes psychological preparation is the top priority for Southgate's squad in the coming days.
Dier played the anchoring role at Wembley, while Henderson is expected to start in Thursday's farewell friendly against Costa Rica at Elland Road, but decision time is looming for the Group G opener against Tunisia.More news: Natural disaster hits Kilauea summit, sending ash plumes up to 8,000 feet
"With the (England) teams I played in, the (Manchester) United group were exceptional, but outside of that it was only Tony Adams who started at Arsenal and was there all the way through. They have to keep working, not satisfied with the level we're at, and keep improving".
England's Raheem Sterling speaks during the media day at St George's Park, Burton.
"Pressure is what you perceive it to be", Southgate said.
"We have this situation because of a lack of education, generally speaking".
"A lot of countries do believe that England are a big threat in the World Cup", the Tottenham forward said. "Some people want it and some people don't, so let them prepare in their own way, make sure we're ready and focused". "We have personal support, team support and official protocol in place", Southgate told a news conference. You want to be in games that matter. Two of them had suffered incredible injuries while serving, and another once he had returned, and yet a couple are running marathons or rowing the Atlantic.