Nigel Clough insists the Blades will keep fighting for the final play-off berth in League One until it is mathematically impossible.
Speaking ahead of United's Easter Monday clash on the Wirral against relegation troubled Tranmere Rovers, Clough thinks United need 12 points from 12 to challenge for sixth spot.
He remarked: "Realistically we will have to win all four matches to have a shout of sixth spot. Let's put 71 points on the board and see if Peterborough can get the points they require.
"We have got that game in hand at Oldham, but Peterborough only need a win and a draw from three games, so we will concentrate on ourselves and see what happens there.
"We will freshen things up at Tranmere, Stefan Scougall got another knock and Bob Harris will miss out so we will probably have to make changes anyway."
On the task that awaits United at Prenton Park, the Gaffer added: "Monday will be similar to the Stevenage game, they are at home after suffering a setback at Gillingham on Friday and their fans will be right behind them.
"They will be scrapping for every ball, every throw-in and it will be down to us to handle ourselves professionally again.
"It is so tight at the bottom and things can change quickly, so Tranmere will know they need a positive result, but all we can do is take care of ourselves."