missed tactical-shot

Feb 12, 2016, 8:55 PM |
each player had 10min for the whole game...this is the possition after 20.Nd2?:
Sorry for my bad english,
here the link to the actual game, after 20.Nd2?, i played a6? and missed this tactical-shot...but i still managed to win, after the oppening i was worse, than i managed to come back and outplay him, at the end he blundered and resigned....: