Robbie Neilson felt his side were bullied by AFC Wimbledon as his MK Dons side went crashing to a 2-0 defeat at the Cherry Red Records Stadium.
Second half goals from Jake Reeves and Lyle Taylor gave the home side a much-deserved victory as Dons failed to live up to expectations in every way.
With a vocal home support behind them, the home side were in total control in the second half, and fully deserved to take all three points.
"We got bullied, and it wasn't good enough," said Neilson afterwards. "We have to get better, get wins and get to safety this season, and then we can build.
"I'm really disappointed. I felt we passed the ball really well in the first half, but we didn't stand up to the game in the second half.
"It's not good enough that we lost the game, but the first half performance wasn't as bad as the result suggests. Harvey (Barnes) had a really good chance, but we didn't take our chances. It's the small details that sometimes don't go your way.
"AFC Wimbledon came out and pressed us really high, but we continued to do what worked for us in the first half. We made it easy for their defenders in the second half and it let them become aggressive and bully our centre forwards. You have to be able to put defenders under pressure at this level. And we didn't do that tonight."
In the first meeting between the two sides in London - the fifth in total - Neilson refused to blame the occasion for Dons' failure to perform.
He added: "I don't think so, we showed that in the first half. This is a derby, but there were no issues, before, after or during. This is a huge disappointment for us, but you have to move on quickly."
The result leaves Dons just six points clear of the relegation scrap, and Neilson knows his side must start picking up points again, having picked up just six from 24.
He said: "We are where we are - we knew that when we came, the key was to stay up, build and try and push. But now we have a massive game on Saturday against Coventry.
"We're going through a difficult time, but we have to win on Saturday. We wanted to win today, but we haven't and now we move on. I think we have to get to 50 points, and from there we can move on. The sooner we get there, the better. It was extremely difficult tonight, but we've got to move on to it.
"It has been a difficult season for everyone. But the key is to stick together and making sure we remain positive - get to the end of the season and rebuild."
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