Rotherham assistant manager Richie Barker said the players were "devastated" after they threw away the lead in a 2-1 loss to Norwich.
Barker was leading the side with manager Paul Warne at home after a member of his family had tested positive for coronavirus.
Warne would have suffered a whirlwind of emotion in the game against his boyhood side after the Millers took a third minute lead before conspiring to hand all the points to the visitors.
Freddie Ladapo's smart finish put Rotherham ahead. The striker blew a chance to double it as Tim Krul guessed right and denied him from the penalty spot after Adam Idah had fouled Clark Robertson.
A string of saves from Jamal Blackman frustrated the visitors with the Chelsea loanee denying Marco Stiepermann and Adam Idah while Jordan Hugill was cursing himself after blasting over from close-range.
Rotherham skipper Michael Ihiekwe was the first to beat Blackman as he turned in Max Aarons's cross. His centre-back partner Angus MacDonald was the next to take on the villain role as he received a straight red card for a wild lunge on Oliver Skipp.
Norwich then managed to nick the victory five minutes into added on time as Hugill beat Blackman from the spot after debutant Florian Jozefzoon had clumsily brought down Emi Buendia.
Barker said: "It's a hard one to take, no matter the time of the goal, because of the performance. It was around four key points, the penalty miss, the own goal, the red card and the penalty.
"I am immensely proud of the players. Things just didn't go our way.
"Unfortunately our best two performances of the season have been home defeats. The players have to take confidence from it. We have more than matched and competed with Norwich.
"The lads are devastated because they wanted to do it for the manager because they are well aware of the manager's Norwich connections. They are devastated because of the effort they have put in. It's a monumental effort for no points.
"I thought we had the two best chances after we went down to 10 men. A lot of things worked towards us not winning the game.
"We face-timed Paul before the game and at half time. He said it was even worse watching it from home but he will be proud of the players."
Norwich head coach Daniel Farke said it was a boost for the team's spirit.
He said: "I have to give plaudits to Rotherham. They have confidence from promotion.
"They were brave, aggressive and pressed us with intensity. I also like the performance from my team. Many, many compliments to the mentality of my players. I prefer it if we scored earlier to make it a bit easier.
"It feels like a massive win. There is no replacements for wins. With this three points we are in a solid position.
"It was a win for team spirit and togetherness. We had the worst start.
"It was an unnecessary penalty to give away but he (Idah) gave the referee a decision to make.
"We created so much in the first half. We could not create more but we were still unable to score.
"I told them that if they kept going we would drive away with three points. It feels massive."