Boss frustrated by missed chances at The DenNeil Harris shared his "overwhelming disappointment" after watching Rochdale come away from SE16 with a 3-2 victory thanks to Ian Henderson's injury-time penalty.
The Dale striker scored in the 92nd minute to condemn Millwall to their first League defeat at The Den in 13 games - a devastating finish to a match which saw Ben Thompson sent off for a second yellow card midway through the second period. Callum Camps gave Keith Hill's side an early lead against the run of play but The Lions hit back through Aiden O'Brien and Lee Gregory (penalty) within nine first-half minutes, only to concede a leveller shortly after the hour mark when Calvin Andrew headed past Jordan Archer.
"We were in front and had chances, lots of them," Harris said afterwards.
"We should have been out of sight and then that comes back to bite you.
"Overwhelming disappointment is what I am feeling because we lost the game. But I've got no qualms about either penalty decisions as both were right.
"We are scoring goals at the moment but not shutting them out at the other end. We have to be better as a team at doing that and, as I've said before, get back to that clean sheet mentality which is so important.
"Every game in this League is so important and we have to quickly get back to our best."
O'Brien was forced off during the first-half with an injury and Harris provided an update on his fitness.
"We are hoping it isn't long-term damage," the boss added. "Short-term it was enough to force him off the park so he's obviously a doubt for Tuesday. We will miss Ben Thompson through suspension so will have to see on Monday what shape we're in going to Port Vale on Tuesday night."
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