Brentford boss Mark Warburton was "embarrassed" by his side's performance as their blushes were spared as they saw off plucky League Two Dagenham & Redbridge in the Capital One Cup first round.
The Bees got the better of the Daggers last year in the competition, but that could not match this drama as the game finished 6-6 after extra-time.
Although his side emerged victorious 4-2 on penalties, the Brentford boss was less than happy with how his side went through.
Warburton said: "It's embarrassing being ahead on so many occasions and not seeing the game out, but we'll come back and learn from it.
"We could have had a lot more goals than we did and to then suddenly concede one just before half-time through some sloppy defending and poor defending. I am not sure I have seen anything like that before in my time in the game.
"We will learn from it though and there were some positives in terms of the youngsters like Montell Moore who is out on his legs.
"Tommy Smith tweaked his groin so we were almost down to nine at the end there - but the fact is we have to do better than that."
Daggers counterpart Wayne Burnett was more than pleased with the way his team forced their way back into the match after finding themselves 2-0 down after nine minutes.
He said: "After 10 minutes I thought this was going to be an onslaught but we showed really good character to get back into the game.
"We scored some decent goals and I am pleased with that - and if you score six goals you expect to win the game but I am disappointed in the manner in which we conceded some of the goals.
"It was very unlike our defence but we showed real good character and work ethic I am so proud.
"At 6-5 you hope you can see the game out but the state of this game was unbelievable.
"I can't remember being involved in a game like it."
Stuart Dallas' quickfire double put Brentford in control, and though George Porter pulled one back, Nick Proschwitz restored the two-goal cushion.
Ashley Chambers gave the east London hosts hope just before half time, and Andre Boucaud's 25-yard strike saw them level .
Brentford substitute Andre Gray scored a fourth, but Ashley Hemmings forced extra-time.
Moore restored the Bees' lead in extra-time - only for Jamie Cureton to make it 5-5.
The Daggers went in front for the first time when Hemmings netted his second goal of the game but Harlee Dean forced penalties.
Jack Connors and Chambers missed for the hosts in the shoot-out and Bees skipper Kevin O'Connor slotted past Liam O'Brien to ensure the visitors progressed into the second round.