The league table suggested there was little to choose between these teams and so it proved in a close-fought battle at Boundary Park.
Oldham and Wednesday both missed a host of chances, but Scott Vernon made one count for the Latics and emerged as match-winner.
Vernon struck after 17 minutes, burying a powerful header from six yards after left-back Adam Griffin picked him out perfectly from the left.
Both sides went on to create plenty of opportunities but their finishing did not match the approach play.
Oldham almost doubled their lead within two minutes of Vernon's goal as midfielder Paul Murray shot from the edge of the box and saw his effort clip the post.
Ernie Cooksey then tested the visiting keeper, but Wednesday came into it when Guylain Ndumbu-Nsungu headed wide from close range.
Ndumbu-Nsungu was the key man for Wednesday and his dipping shot gave Oldham keeper Les Pogliacomi an awkward save to make before the break.
He also struck the woodwork from 16 yards out as Wednesday piled forward in the second half, while substitute Adam Proudlock capped a disappointing afternoon personally by putting the best chance wide from six yards with only five minutes left.
Wednesday manager Chris Turner said: "If you are going to lose it's better to do it playing good football and that's what we did.
"We didn't deserve to come away with nothing and we will start picking up points more often if we keep playing like that.
"Ndumbu-Nsungu is a very exciting player and he gave Oldham problems all afternoon. Unfortunately, we didn't make the most of it.
"The goal was very disappointing from my point of view because we went to sleep down our right-hand side and then Dean Smith lost his man in the middle." John Sheridan, who played against his old club and is building a good record as the caretaker-manager at Boundary Park, was delighted with his team.
Sheridan said: "They worked ever so hard and our defending was solid when it needed to be.
"It was good to see Scott Vernon get the winner because he is an intelligent young player who can go a long way if he keeps developing his game."