Callum McManaman's early goal was enough to secure a 1-0 win and take the pressure off the final game against Blackburn at the weekend.
Back in December when Uwe Rosler took over, the German promised he would achieve a playoff place for chairman Dave Whelan and he is delighted to have delivered on that proise.
Speaking to the Wigan Evening Post, Rosler said: "I promised the chairman when I joined that we would get into the play-offs, and m players, my squad, has delivered.
"I compliment the players who were on duty an the players who have played in the other games. It has been a monumental effort, considering where we started in December, but the job is not yet complete.
"A lot of people said that it was impossible for us to achieve the play-offs with the cup run, and we did by itilising the squad and managing players coming back from long-term injuries - like Gary Caldwell, Shaun MAlone, and Roger Espinoza.
"It was only possible, the way that we did it, by everybody contributing and I am very proud of my players.
"We will now have two days of active recovery. We are not shutting down the engine completely. We will make sure that we will have a very strong and motivated team pushing for a win at Blackburn Rovers."
The Latics look odds-on to finish in fifth place in the table which would mean play-offs ties against Q.P.R. However should Reading win, and Latics lose, at the weekend then Rosler's men would finish in sixth and face ties against Derby County.