That is the verdict of Addicks goalkeeping coach Andy Marshall, who watched Naby Sarr’s routine backpass roll past the academy product.
But Phillips responded with an excellent save to deny Grant Leadbitter. And my full-time the 23-year-old was leading the on-pitch dancing at Wembley as goals from Ben Purrington and Patrick Bauer took the South London club into the Championship.
Marshall – asked about the Charlton number one’s mistake – said: “It happens – and it happened. And if it is going to happen then it happened at the best possible time – because there was still 85 minutes left.
“He has been phenomenal for us this season. He has taken his ups and his downs. He has had to come in and out of the side and he has learned his lesson. It was a massive learning curve for him at Wembley and what I will say is that it showed a true strength of character. Because 10 minutes later he made a great save down to his left, which for me would have killed the game.
“He carried on getting the balls passed back. So a massive amount of credit to the kid, he showed true character and professionalism on everything we have been working on all season. And it came to fruition for him.
“I said to him at half-time: ‘You know you are going to get dog’s abuse when you go down the other end and it is about how you deal with that’. He said: ‘Yep, no problem’. And there is nothing more that needs to be said.
“It was the worst thing as a goalkeeper that you visualise happening. We have all been there, so I know what he was going through and the lonely place you are in for a few minutes. But the good thing was it was only there for a short period of time.
“The way he turned it around was phenomenal, the way he put his hands up to Naby Sarr and went: ‘It was my fault’. The kid learned a lot. But he has got to realise we are going to look forward and the Championship is that [pointed out to the Wembley pitch] and a lot more every week.
“He has earned his stripes and he has earned his place in the team. It is down to Dil to keep it.”
Phillips had been understudy for most of the first half of the campaign – only getting another crack when Jed Steer was recalled by Aston Villa.
Steer was a Wembley winner a day later as the Midlands club beat Derby County to secure a return to the Premier League.
Phillips’ form kept the more experienced Chris Maxwell – signed on loan in January from Preston – in a watching brief.
Marshall said: “Where Dil believed he was at at the start of the season was a completely different place to where I believed he was at, and the place I believe he needed to be at to cope with the rigours of this level and the next level.
“That was a learning curve for him, and it was a tough learning curve. Eventually he responded to it and when he responded to it was when we saw the improvement and saw Dillon Phillips become the goalkeeper he is starting to become. But it is step-by-step.
“Sunday was about enjoying it – but there is a lot further to go yet.”
Charlton will need to add in the goalkeeping department with Maxwell returning to Deepdale.
“From my point of view, Dil has got the shirt,” said Marshall.
“It is down to him to lose it.
“I will do what I can do with him and I know he will come along on this journey that he started at the start of this season.
“We will have to look to strengthen and bring new players in, a new goalkeeper in, a new centre-half, a new centre-midfielder, a new centre-forward to strengthen to the squad.
“Dillon is a work in progress. We have reaped the rewards of how Dillon is playing. But I say to Dillon and all the goalkeepers: ‘There is another step – and then another step after that’.
“To push this club higher means standards have got to improve dramatically and drastically. The Championship is a relentless league and the Premier League is a ruthless league which takes no prisoners.
“I’ve kept stressing that the level we had been at isn’t the level we require next season or the season after that.”