Visitors Melton Town — two steps below Worksop in the non-league ladder — struck twice in added-on time to knock out the Tigers 2-1.
It was their first competitive loss since 22nd December last year.
The surprise defeat also ended a run of 22 straight wins ahead of Worksop’s first season in the Evo-Stik NPL South/East Division after last season’s promotion from the NCEL.
“We shot ourselvesin the foot, which happens a lot to us. We got ourselves into a (good)position, had chances and then let it slip with some awful defending,” Humphreys said.
“That’s our wake-up call, a massive wake-up call to the lads. We have had words. I don’t think a lot has to be said.
“We have to pick ourselves up and go again.
“We thought it would be quite a comfortable game, but it is the FA Cup and things happen. We have to take it on the chin and move on.
“That was a team we thought could do a job... there will be ups and downs this season as we have stepped up a level. We believe in the lads we have got, that’s why a lot of them are still here.”
It all went wrong for the Tigers, who had led from the second minute, when Josh Hill’s low drive was spilled by keeper David Reay into the path of Kadeem Price, who fired in for the visitors.
Then six minutes into toppage time Zac Munton won possession off Steve Wankiewicz and pulled it back for Jordan Lever to hit the winner — Melton’s first in the FA Cup.
Yet Worksop had made a great start when Lynton Karkach burst down the right and floated a cross towards the far post in the second minute.
Craig Mitchell’s looping header was pushed on to the bar, but the forward thumped home the rebound.
In the 70th minute a terrific save by Reay, palming away a shot, looked to have ensured progress before the late drama.