Neil Warnock was left fuming after seeing his wasteful Cardiff side twice throw away a winning position against Millwall.
The Lions came from behind thanks to Tom Bradshaw's brace to earn a 2-2 draw and move five points clear of the Sky Bet Championship drop zone.
Danny Ward needed just 11 minutes to put the visitors ahead, but Bradshaw would strike either side of Junior Hoilett's stunning effort to share the spoils.
"It is probably the most frustrated I've ever been this season, and there have been one or two moments," said Warnock.
"It is scandalous really. I just don't know what to say.
"I have never felt so comfortable at Millwall. We had shot after shot after shot, chances from corner kicks and everywhere.
"We were so charitable with the two goals and it is unbelievable really, so I am disappointed, especially as this is as good an away performance as you are going to get at a place like this. I can't see many teams dominating as much as we did.
"I think the first chance they had they scored and the second one came from our own free-kick.
"We played well, we did not want to get sucked in – I know I am called physical. We wanted to try and play if we could.
"There is not a lot to complain about other than two goals conceded."
The Bluebirds drew first blood, Hoilett swinging in a cross from the left and Ward nodding home from close range after 11 minutes.
Bradshaw popped up on the right of the box and fired home a deflected shot to level shortly before half- time.
The Bluebirds made their dominance count when Hoilett curled home a brilliant effort.
Millwall were rewarded for a rare foray forward as Bradshaw latched onto the ball in the box, jinked past one defender and lashed another equaliser high into the net.
The hitman could have had a hat-trick minutes later, but from a tight angle shot straight at Neil Etheridge.
Millwall caretaker manager Adam Barrett said: "I am just delighted with the character of the team after a difficult game on Saturday to come back twice tonight against a very strong Cardiff team.
"It has been a real topsy turvy two weeks and to come away with four points from the three games I am delighted for the boys and for everyone at the club.
"With a new manager, hopefully, he can come in and take us forward. I am delighted with the team and the boys.
"That is what we signed Tom [Bradshaw] for and we knew what we were getting. Full credit to the lad, he has been fantastic, and he has been working extremely hard behind the scenes and now he is getting his rewards and we are starting to see what a very good player he is.
"It is an exciting time for the club, I am really looking forward to working with him and learning from him, an experienced manager is coming in and I think Gary [Rowett] will bring a fresh outlook."
