Rotherham manager Steve Evans was fuming at the penalty decision which handed Peterborough a 1-0 victory at the New York Stadium.
Evans claimed defender Kari Arnason was pushed and forced to throw out his arm and handle the ball, although Grant McCann made no mistake with the resulting spot-kick.
Rotherham had the lion's share of the chances in the opening 45 minutes but failed to make the most of them and, after the goal, they produced a spirited rally but fell short of an equaliser.
"We thought it was a foul on Arnason and when we have looked at the DVD it is a clear foul," Evans said. "We have been on the end of a shocking decision but these things happen I suppose.
"It's hard to take but we have to take the positives.We had some wonderful play, we opened them up time after time and at the end we laid siege.We missed a host of chances - seven of eight clear-cut chances.
"Theres a lot to be pleased about and if we continue to work as hard as that we will do well . They are the best team in the division in my opinion and we have taken them apart.
"If we play as well as we played here we will have a season to remember. We hurt now but we will bounce back."