Harris felt Millwall 'were better than Brighton' despite FA Cup exit
Millwall went 2-0 up through Irishmen Alex Pearce and Aiden O'Brien before Jurgen Locadia reduced the deficit.
An error from stopper David Martin saw Solly March's cross float over the Lions keeper's head to level in the 95th minute of the game.
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Hide AdWith no goals in the following extra period, Jake Cooper was the man unfortunate to miss his penalty as valiant Millwall exited the cup at the quarter-final stage.
Harris said: "What an outstanding performance for 94 minutes.
"First and foremost I feel for Dave Martin because he was excellent throughout the game. (He was) commanding his box, made some saves, but he's made a slight error of judgement and has cost us.
"He's a top pro and one of the nicest guys I've ever come across in football as a player, coach, or manager.
"The way my team played - the running ability, some of the play with the ball, the two goals we scored - showed great play.
"What gives the most pride was that we were better than Brighton today."