Nigel Clough's first taste of the Johnstone's Paint Trophy resulted in victory.
The Blades, despite making 11 changes, overcame the challenge of Sky Bet League Two's Hartlepool United.
Jose Baxter opened the scoring, Michael Duckworth levelled with the aid of a deflection before Jamal Campbell-Ryce popped up to net the winner with eight minutes to go.
Chief Clough took the unusual step of naming his team and subs for this game more than 24 hours before kick-off in the north east. Goalkeeper Turner made his first appearance for the Club and De Girolamo, one of three teenagers in the starting line-up, made his full debut in a Blades shirt.
The early action was in and around the Hartlepool box. Campbell-Ryce was the first to test Flinders and Porter was offside as he latched on to McGinn's forward pass.
A long range header from Woods caused Turner a nervous moment but United were definitely the more offensive outfit. Reed sidefooted wide after Porter laid off and Baxter, from a deep position, was causing problems for Hartlepool.
Harris picked up a yellow card and Brobbel's effort was deflected safely into the hands of Turner before United took the lead on the half hour. From the left, De Girolamo was involved and Reed added the slightest of touches before BAXTER arrived to the edge of the box late, expertly placing into the net, via Flinders' left post.
Within 60 seconds of the goal, Baxter played in Porter and although the striker slid the ball past the home goalkeeper, he was unable to find the target. Soon after, the same Blades duo were involved to create a chance for Harris but he was unable to add to the lead.
Late in the half, Hartlepool hit back with a couple of chances of their own, Brobbel cut in from the left and shot wide and a 25-yard effort from Green was comfortable for Turner.
United made a change at the break, McNulty taking over from Baxter, possibly a pre-planned move with the goalscorer just back from injury. The first opportunity after the interval fell to Hartlepool and resulted in a goal, although there was an element fortune. DUCKWORTH's 25-yard shot took a telling deflection off McGahey to wrong-foot Turner.
Despite the equaliser, United remained the more likely to add to the scoreline. Flinders was awarded a free-kick when he dropped a Campbell-Ryce cross under pressure from Porter and on 59 minutes there was a number of chances in one move following another Campbell-Ryce delivery, including a Flinders saving from Porter, who was only six yards out.
Just after the hour De Girolamo was replaced by Murphy, who quickly had a shot blocked. United's substitute then turned provider for Porter on 72 minutes but the striker's first time effort was wide.
McGinn kicked away after Hawkins got around the back but the Blades remained on top. Just into the last 10 minutes, following a Davies corner, Basham won the initial header and Murphy acrobatically hit the crossbar, but the lead was restored on 82 minutes.
A ball from the left looked like a comfortable clearance for the Hartlepool defence but McNulty put his head in where it hurts to win possession and play in CAMPBELL-RYCE, who shot across Flinders into bottom corner.
Collins replaced Porter and the defender was thrown into the attack but late on, expectedly, the home side threw caution to the wind. Basham kicked clear when Smith danced into the box and three minutes of added time passed without major incident as the Blades booked a place in the next round, although Brobbel fired at Turner.
Hartlepool: Flinders, Duckworth, Austin, Harrison, Jones, Miller, Woods, Green (Walker 75), Hawkins (Smith 86), Wyke, Brobbel.
Unused: Holden, Franks, Richards, Smith.
Blades: Turner, Harris, Basham, Baxter (McNulty 45), McGinn, Davies, McGahey, Porter (Collins 84), Campbell-Ryce, Reed, De Girolamo (Murphy 63).
Unused: Doyle, Willis, Murphy.