That game in hand is on Tuesday night when Cheltenham Town, who were relegated on Saturday, head to Glanford Park.
A draw or a win would move Scunthorpe back into the play-offs, making the last day visit of Tranmere a winner-takes-all game. Or, more accurately winner-takes-all-but-Scunthorpe-take-all-if-its-a-draw game.
Below are the three possible scenarios for after Tuesday's game:
Scunthorpe win: United will head into the final game only needing to avoid defeat against Tranmere, who will be two points behind. Only a home loss would be enough for the Wirral side to usurp the Iron.
Draw: A point would move Scunthorpe back into the play-offs. Although they would be level with Tranmere, their better goal difference (+16 compared to +13) would be enough. Again, a win or draw on the final day would be enough for a play-off place.
Scunthorpe lose: If United do not pick up a point on Tuesday they will remain outside the play-off positions, one point behind Tranmere. They would then need to beat Rovers on the final day of the season to go above them. Draw or lose the match and the season would be over.