Charlton boss Lee Bowyer could not hide his disappointment after his side were on the receiving end of a Matt Smith stoppage-time winner as Millwall triumphed 2-1 at the Den.
A sixth-minute header from captain Shaun Hutchinson put Millwall in front, but they were pegged back shortly after half-time by Jonathan Leko's smart finish.
The game looked to be heading for a draw but Smith, brought on with just four minutes remaining, rose at the back post to earn the hosts all three points, leaving Bowyer ruing missed opportunities in what he believes was a dominant display.
"I'd have been disappointed with a point! We can't afford to not win this game, because I thought we were the better side," Bowyer said.
"I may be biased but this is what I'm watching, us playing the way we're playing. To come away with nothing is so disappointing. I can't express how disappointed I am.
"I thought we were better than them. I thought we dominated large parts of the game. First half we conceded an early set-piece which gives them something to hold on to but once we started passing the ball then we dominated the rest of the first half.
"Once we equalised I thought here we go, we're going to go and win the game. We were better than them. When we're moving the ball, we created a lot of problems for them.
"Once we equalised we stopped passing the ball, it became more of an even game, but I still felt that we'd go on and win the game, but we end up losing and getting nothing.
"We have to defend better. We've lost this game on two set-pieces. Defending set-pieces is easy, you just make sure your man doesn't score. That's it. It's simple.
"But for some reason their man wanted to score more than our man wanted to defend. And their goalie obviously played really well, but to come away with nothing, that's ridiculous."
The result extended Millwall's undefeated run over Charlton in the league, which charts all the way back to 1996, and the thrilling end to the game excited Lions boss Gary Rowett.
He said: "As a manager you want to win 3-0 and have a really easy afternoon, but if you can't do that there's no more exciting way to win a local derby than in the last two or three minutes.
"It was a difficult game, Charlton are a good side. They've shown that this season.
"I think at 1-1 it was a real turning point. People talk about Bart's (Bartosz Bialkowski) save, it's an unbelievable save, but their keeper has also made an unbelievable save so, I think we probably just edged the chances, Charlton edged possession and control.
"They then dropped a bit, and allowed us to get back into it. And then, we're at home, we've got to make attacking changes and try and force the game.
"If you put quality into the box with Matt he's the best in the division in those scenarios. As soon as he comes onto the pitch the players have to avoid just hitting him from anywhere and lacking respect for him as a player. We've got to work it into better positions to get the cross."