Peterborough United lost the services of Erhun Oztumer and Gabi Zakuani to injury and Jonny Edwards to a red card on his debut, but dug in to claim a point on the final day of the season thanks to a Michael Bostwick volley.
The home side found an early breakthrough as Dominic POLEON planted a header in off the inside of the post after a driven cross on nine minutes.
Posh were forced into a change on 20 minutes as Erhun Oztumer was stretchered off with a foot injury.
Michael Bostwick drove wide and Ricardo Santos headed wide before Joe Newell cut inside from the left and drilled a shot just wide of the near post.
Posh were forced into another change four minutes before the interval as Gabi Zakuani limped out of proceedings with an ankle injury. Shaun Brisley was his replacement.
Jonny Edwards fired wide with his left-foot before Bostwick headed wide from a corner.
Moments after the interval, a stinging Bostwick drive from a free kick was punched in the air by Coleman with Santos heading the rebound wide of the target.
Mike Jones tested Alnwick with a well executed volley on 63 minutes, but the Posh goalkeeper did well to hold on to the skidding effort.
Posh were reduced to 10-men on 65 minutes as debutant Edwards was shown a straight red card for a late challenge on James Wilson.
Dave Robertson made his final change on 71 minutes as Marcus Maddison replaced Da-Silva Lopes.
On 76 minutes, Posh drew themselves level as a corner from Newell was flicked away by an Oldham defender but the ball landed on the volley for BOSTWICK who fired past Coleman.
Full-Time: Oldham Athletic 1-1 Peterborough United
Oldham: Coleman, Brown, Kelly, Jones, Poleon, Philliskirk, Winchester (sub Tuohy 69min), J. Wilson, B. Wilson (sub Dieng 87min), Turner (sub Bove 60min), Gerrard. Unused subs: Kean, Elokobi, Mellis, Woodland.
Posh: Alnwick, Smith, Bostwick, Oztumer (sub Payne 20min), Washington, Newell, Edwards, Santos, Zakuani (sub Brisley 40min), Anderson, Da-Silva Lopes (sub Maddison 71min). Unused subs: Henry, Burgess, Beautyman, James.
Attendance: 3,943 (324 Posh fans).