Gareth Southgate hailed match-winner Raheem Sterling for standing tall amid a "mixed bag" of an England performance in Iceland.
With Harry Kane off the field, Sterling won and converted a 91st-minute penalty to secure a 1-0 Nations League victory in Reykjavik but there was a further twist in the tale.
Joe Gomez fouled substitute Holmbert Fridjonsson under a long ball in the England box, giving Iceland a chance to level deeper into stoppage time, only for Birkir Bjarnason to blaze wildly off target.
Both sides were down to 10 men by that point, with Kyle Walker and Sverrir Ingason having seen red.
While Ingason's second booking came when he handled Sterling's goal-bound shot in the decisive moment of the match, Walker departed 20 minutes from time for a rash tackle on Arnor Ingvi Traustason when he was already on a yellow card.
"The sending off is a key moment because I felt we were in even more control in the second half," Southgate told Sky Sports when giving an honest assessment of England's ultimately successful bid for a measure of revenge against the nation who humiliatingly knocked them out of Euro 2016.
"It's very difficult to win games of football at any level if you're down to 10 men. That's a lesson we have to learn, it was an unnecessary red card.
"Then the response was great, we managed to stay in good possession of the ball, looked a threat.
"We get the penalty and I thought Raheem's desire through that period and drive was outstanding. It was great that he took that penalty under pressure.
"And then another lesson we have to learn because to invite the ball as we did and defend it the way that we did was really poor play. In the end we get away with it.
"It kind of sums the week up. We've had so many challenges, it's been so difficult to piece everything together."
Walker did not feature for England last season and, in a frank interview with Sky after the game, he conceded he had done his long-term international future no favours following an incident for which he took full responsibility.
"He said the same in the dressing room," Southgate said. "He realises, as an experienced player, those sort of challenges invite the opportunity for the referee to make a decision and it was the right decision.
"I've no complaints in terms of the officials on the penalties or the red cards.
"We've talked a lot over the years about discipline. In tournaments especially, if you go down to 10 men, then the number of times we've gone out of tournaments because of that has proved critical.
"It's not something we want to see again."
Walker will be suspended when England continue their Nations League Group A3 campaign in Denmark on Tuesday.Published 06 Sep 2020, 02:00 IST