Peter Taylor has called for patience from supporters after Gillingham's 1-1 home draw against Brackley in the FA Cup.
The Conference North side were within seconds of reaching the second round for the first time in their history after a second-half own goal from Joe Martin had put them in front.
Goalkeeper Billy Turley, the hero of the last round, made a number of saves to preserve the lead against their League One opponents.
But substitute Bradley Dack found room in the seventh minute of added time to volley home from Adebayo Akinfenwa's header, sparing Gillingham's blushes and forcing a replay.
"Fair play to Brackley, they played with lots of confidence," said caretaker boss Taylor.
"They showed what they're capable of and they played better than us.
"The most pleasing thing for me is that we kept on going. It wasn't our day, we looked nervous, but we got a draw out of it.
"Fans have got to be realistic here. I've come in as interim manager and I'm trying to change a few things. It's going to take a bit of time and some supporters will be patient with that.
"I don't think some fans are helping the cause right now. I think there are too many who want to have a go at the manager or the players, and I don't think that's helping. I think they could be a touch more patient because of the situation here.
"The FA Cup always has shocks and I'm sure that's because teams get nervous playing against those from lower divisions than them.
"The players will know the strength of Brackley and the replay will be a tough game, but I'm pleased to be in the hat."