An abject display from the Railwaymen had left Lee Johnson's far from impressive outfit cruising to a vital victory, until the fourth official's board showing seven added minutes inspired a last stand from the hosts.
Chuks Aneke, a passenger for most of the afternoon, curled an exquisite free-kick towards goal which Paul Rachubka did well to claw over his crossbar.
But the Oldham goalkeeper was beaten straight from the resulting corner when Davis planted his head onto George Evans' cross with 94 minutes on the clock.
It was a barely deserved leveller and one which visiting boss Johnson felt was a direct result of the "ridiculous" amount of time added on by referee David Phillips.
Crewe barely mustered a shot on goal until their late rally and while Oldham did at least make young keeper Ben Garratt work for his corn, they remain in the relegation dogfight also.
"We were second best for most of the game and Oldham deserved to beat us," admitted Alex boss Davis.
"They were pressing us quite high and they had a plan to stop us. We knew they would make it difficult for us to break them down.
"The pitch was poor so we decided to bypass the middle of the pitch and play it longer, which isn't our style really. But we weren't able to get Chuks on the ball or Brad Inman into the game.
"Everything was in front of their back four and we never got in behind them. I thought it was going to be another blank day for us and I was disappointed with that performance.
"We were disappointed with their goal too as it came from a breakaway.
"But we kept going and the seven minutes added on was a result of a lot of time wasting so it backfired on them a little bit. I was pleased to see that (Davis goal) as I couldn't see any way our front four players scoring."