The visitors enjoyed the majority of the early possession but it was Maribor who had the first opening of the match when Zeljko Filipovic hit a shot that flew narrowly wide in the sixth minute.
Callum McManaman almost found Powell with a low cross from the right flank, but the Maribor defence managed to clear the ball to safety.
Jordi Gomez almost broke the deadlock on 35 minutes when his free kick from 20 yards struck the post.
Four minutes before the break Wigan were awarded a penalty after Powell had been fouled in the area, and Gomez converted to give Uwe Rosler's side the lead.
Maribor were awarded a penalty of their own within a minute when Chris McCann handled the ball, and the Wigan midfielder was sent off for a second bookable offence.