It’s the first time the two teams have played each other since August 13, 2014, when the Blades hosted Mansfield in a League Cup first round tie when the sides were in League One and League Two respectively.
Ironically, the United manager that night was Nigel Clough, who is now of course the Stags boss.
Andy Butler put the Blades ahead seven minutes into the second half, heading home a Ben Davies corner.
Clough’s relief was short-lived, though, as Alex Fisher brought Mansfield level just four minutes later with a powerful right-foot shot.
The Stags then pushed for a winner, with Blades goalkeeper Mark Howard keeping out a Sam Clucas effort.
But Marc McNulty popped up with a last-gasp winner to delight Clough with four minutes left and set up a clash with West Ham in their second round tie.
Here, we look at who played for Mansfield that day and then where their careers took them after leaving Stags, with some of them pictured during the game itself.
9. Alex Fisher - Forward
Scorer Fisher joined Stags after spells in Belgium and Italy and went on to feature for several clubs in England and Scotland, and is currently with Bath City. Photo: .
10. Liam Hearn - Forward
Hearn rarely featured for Mansfield before moving on to Lincoln City and then dropping into non--league. He currently coaches at Sheffield United having also coached at Derby and Mansfield. Photo: .
11. Lee Beevers - Midfielder
Beevers had three years with Stags before moving on to Lincoln City and then into non-league, ending his career at Matlock. Photo: .
12. Sam Clucas - Midfielder (sub)
Clucas has gone on to enjoy a great career in the EFL with the likes of Hull, Stoke and Rotherham and is currently with Shrewsbury Town. Photo: .