NEIL Harris admitted Barnsley deserved to pick up three points at The Den on Saturday afternoon, Millwall's first defeat in five games, but said he was "delighted" with how his side have performed so far on their Championship return.
The Lions' three-match winning home streak came to an end, as a double from Tom Bradshaw and Mamadou Thiam's late penalty after Lee Gregory had equalised from the spot just before half-time gave Barnsley a fifth successive win over Millwall.
Harris thought his side weren't at their best against Barnsley.
He said: "I was disappointed with the performance, of course, and disappointed with the outcome. Was it a game too far for some of my players? Looking back now I'd say yes, obviously it was.
"I take responsibility for that because I pick the team. My players have been in excellent form individually and collectively and deserved the opportunity to play.
"If you were to take anything out of today [it] would be if we're not at our best Millwall standards in every fixture in the league this season we can get beaten at any time, home or away.
"Today we weren't at our best. We weren't at our best as a defensive unit, we gave away the ball cheaply and we got hurt on the transition. Ultimately if you give good players at this level the opportunity they're going to take them.
"Barnsley deserved to win the game because they took their chances. I'm really disappointed with the performance and the result but ultimately over the first 11 games of the season I'm delighted with what I've seen from my group."
Harris felt Gregory's goal going into the half-time interval could have proven decisive, but the Lions boss emphasised Millwall can't dip below the standards they have set this season.
"I don't think there was a great deal of quality in the first half from both teams. However, scoring on the stroke of half-time gave us a bit of momentum," Harris said.
"But I said to the players it wasn't good enough, we had to be better. I thought the first 15 minutes of the second half we were at our best. We played in their final third.
"And then, sucker punch, we concede. It changed the complexion of the game but even then I wasn't really worried. I could see us getting back in the game.
"The third goal was a really poor goal to give away and it kills the game, kills the atmosphere in the stadium.
"It's a learning curve for us, definitely. The boys have set their own standards. To get into the top half of the league Tuesday night, having had a really tough run of fixtures as well, maybe everyone just got a little bit carried away.
"Everyone thought, 'we're not a bad side, we can be alright in this league, we can just turn up against Barnsley and win the game'.
"Well, me and my staff didn't think that. If my players or the fans had any inkling about that, that's gone out the window for the rest of the season.
"Anybody can beat us at any stage throughout this season – unless we are at our best, when we will win games of football."
Image: Millwall FC