The score line, coupled with results elsewhere, sees Dale still in with a chance of clinching a top six finish, should they beat Bradford City on the final day of the campaign.
Callum Camps rifled an effort into the roof of the net to open the scoring in the 13th minutes, but Peter Clarke headed home in the second half to earn a point for the Latics.
Rochdale showed their attacking intent from the first whistle in their final away game of the season, after winning a corner just 23 seconds into the match.
Jamie Allen broke away up the left and sent the ball to the near post for Calvin Andrew, who was kept out by Connor Ripley.
Dale’s pace was proving to be a real threat and after another swift move forward, Ian Henderson had a shot blocked and deflected away from goal, allowing the scrambling Ripley to smother.
Momentum was building and ten minutes later, Rochdale opened the scoring through Camps. Nathaniel Mendez-Laing showed great strength to see off his markers, and after getting to the byline, he pulled the ball back to Camps, who rifled into the roof of the net from 10-yards.
The home side’s best chance of the half came in the 17th minute when Ousmane Fane hit a powerful snap shot at goal. He was easily kept out, though, as the alert Conrad Logan got down low to hold.
Soon after, Ripley was forced to tip Andrew’s header over the bar, after the Dale forward got on the end of a Henderson delivery.
On the half hour mark, some brilliant defending saw Keith Keane and Harrison McGahey combine to prevent Ewrin latching onto the end of an Aaron Amadi-Hollway pass which would have seen him in on goal.
Immediately up the other end, and Henderson almost doubled Dale’s advantage with a clipped effort which curled just over the bar.
Before the half was out, Henderson came close again as he attempted to lift the ball up and over Ripley, who rose to collect.
HT: OLDHAM ATHLETIC 0-1 ROCHDALE
Both teams defended resolutely during the opening exchanges after the break, meaning clear cut opportunities were at a premium.
The best chance of the half since the re-start fell to Fane shortly before the hour mark, but he could only head wide of the upright.
As news filtered around the ground that results elsewhere were going in Dale’s favour, they were dealt a blow as Peter Clarke powered a header beyond Logan at the back post from a free-kick to level the scoring.
With Rochdale in need of a goal, they ramped up the pressure, and in the 73rd minute Allen stung the palms of Ripley after bursting into the area.
Mendez-Laing came close soon after as his drive was blocked and sent just wide of the upright, and before the game was out, he saw an effort deflected over the bar.
FT: OLDHAM ATHLETIC 1-1 ROCHDALE