Paul Tisdale was surprised and disappointed by his MK Dons side after they failed to deal with a rejuvenated Grimsby side in the second half of their FA Cup clash on Saturday.
Leading 1-0, courtesy of Kieran Agard's seventh goal of the season midway through the opening period, Dons were shell-shocked by a wonder-goal from Elliot Embleton five minutes into the second half. Strikes from Wes Thomas and Charles Vernam followed as Dons were sent crashing out of the FA Cup in the first round - the first time they had done so since 2010.
Tisdale named the same side who had comprehensively beaten Crawley 4-0 in League 2 a week earlier, and said his side must learn to cope with pumped-up opposition in a better way.
"It's disappointing, especially being a goal up at half time, and I don't think the second half defensive display was us. But Grimsby deserved it, they had a real intensity that we just seemed to lack in the second half. They deserved their win.
"I have little to criticise in the first half. We had a healthy breeze behind us, the surface was good, we played some good football and probably deserved that goal. 1-0 up at half time, it was a lesson to us – the opposition always have something they can do in the dressing room that we are not privy to, and we did not respond well enough. We have to learn from it.
"We did not play quite as normally expect. We conceded three goals, and I'm really disappointed by that. It has been a strong part of our personality so far. The players deserve a few credits. Today, maybe it was one of those days but we have to respond quickly."
While Dons' undefeated record in the league remains at nine games, Tisdale said he wanted better from his side at Grimsby.
He added: "We put the same team out that won at Crawley last week so there's no part of our preparation that was differing from 'same again.' I've had very few reasons to be disappointed by my team so far, but today was a bit of a disappointment. It needs to be part of our psyche, we shouldn't forget it and it will make us a better team hopefully.
"We will look at all the dimensions, emotions and dynamics. We've done pretty well so far, but I'm not taking anything for granted. It's the FA Cup, but it's a game of football against a team in our league and we've been pretty good against teams in League 2 this year. I wanted better."