Luke Moore scored the only goal as League Two outfit AFC Wimbledon shocked League One hosts Scunthorpe in their FA Cup first round replay.
Both sides had chances in a tense encounter before Moore scored a rebound in the second half after substitute Jack Midson's shot had been blocked.
Charles Ademeno could have made it 2-0 but fired over and Garry Thompson had a chance to level the tie saved.
Andy Barcham almost forced extra-time when his deflected cross hit the bar.
The Dons visit League Two rivals Bradford in the second round on 3 December.
VIEWS FROM THE DRESSING ROOMS.
Scunthorpe United manager Alan Knill told BBC Radio Humberside:
"It's a big blow - if you do well in the Cups it helps the manager as there's more finance to bring players in, so it's incredibly disappointing.
"Our last two games have been really painful but I think everybody's trying their best and the players are trying their best and eventually we'll get there.
"I don't feel insecure at all. When you're a football manager you live on the edge every day.
"All you can do is do your best and we're doing our best with the tools we have available."