'We panicked when we went 3-0 up,' he said after City's incredible 3 - 3 draw at Plymouth.
'Three goals should have been enough, but once they had scored we just panicked and decided to lump it instead of the football we have been playing lately.
Chopra, who picked up a 4th yellow card of the season (one more will see him get a one match ban) continued
'Once they were back in it, the crowd got behind them and it was hard for us.
'We panicked and players started to drop deeper and deeper, and until we put that right we will keep on conceding goals.
'We now have a couple of days to work on that before Luton Town on Saturday, because at the moment it seems that for us to score goals it needs to be spectacular.
'And we need to concentrate a lot harder as a team to stop the goals going in.'