United picked up another valuable point but were ultimately frustrated by some inspired goalkeeping.
Gillingham's Stuart Nelson made at least five impressive saves, whilst the Blades also had two goals ruled out. Billy Sharp netted his 18th of the season and Kieron Freeman again scored.
Despite the previous week's defeat, chief Wilder named an unchanged starting XI, new loanee Riley was amongst the substitutes.
The Blades controlled possession early on and were patient, looking to find holes in the Gills defence. Following Oshilaja's foul on Lavery, Duffy's free-kick was partially cleared and Fleck's deflected shot forced Nelson into a save, whilst on 12 minutes quick, neat, footwork on the left saw Sharp head over Fleck's cross.
Gillingham's first chance, on 18 minutes, saw List allowed to progress 30 yards before he shot wide. United were quickly back on top - Duffy had a shot blocked and Lavery was agonisingly close at the near post from Freeman's cross.
A neat move on the half hour saw goalkeeper Nelson quickly off his line to thwart Lavery but the visitors were unable to prevent United opening the scoring on 32 minutes after yet more impressive, nifty passing. Coutts, Fleck, Sharp, Lavery and SHARP again were involved before the skipper fired past Nelson.
As half-time approached United were clearly on top. Gillingham could count themselves fortunate to be just one behind after three more good chances.
Coutts volleyed wide after Gillingham again failed to fully clear a Fleck corner and then Nelson pushed Sharp's shot around a post following Freeman's low cross.
On 44 minutes yet another great Blades move saw Nelson again come to the away side's rescue. Coutts played two one-twos to progress to the edge of the box and put Sharp in but the Gillingham goalkeeper was quickly down to his right to save again.
Gillingham were forced into a change at the break and they came out with more purpose. Jackson's speculative shot was off target before they levelled on 51 minutes. Jackson, Dack and Wagstaff were all involved before WRIGHT danced beyond Ebanks-Landell and clipped over Moore.
United attempted hit straight back and had the ball in the net within 60 seconds but Sharp was adjudged to be offside when heading home Freeman's cross. Soon after O'Connell's deft header from Duffy's free-kick was just off target before the Gills struck again.
On 58 minutes Ehmer touched on Jackson's long throw perfectly for WRIGHT to beat Moore from close-range. Again, within minutes the Blades had the ball in the net, but this time O'Connell was said to be offside as he converted Duffy's cross.
The entertainment value continued and United levelled on 61 minutes. Freeman, Basham and Sharp combined on the right and after Nelson had denied Lavery, FREEMAN continued his run and blasted the rebound into the roof of the Kop net.
United were now back on top. Following a breakaway, Freeman's deep cross was headed into the sidenetting by Lavery and McNulty, on a matter of minutes, saw his shot, following Duffy's pass, saved by Nelson's legs.
Gillingham, though, were still a threat, as emphasised by Ehmer heading wide a Dack corner on 75 minutes.
Two corners in two minutes saw United go close twice. Fleck delivered the first but McNulty's overhead kick was saved by Nelson, who knew little about Sharp's header hitting him just seconds later.
An O'Connell cross was collected by Nelson and five added minutes gave United hope but a Dack volley was only inches away from Moore's right post. Ebanks-Landell went forward in the closing minutes but United were unable to test the impressive Nelson again.
Blades: Moore, Fleck, O'Connell, Basham, Lavery (McNulty 72), Sharp, Done (Scougall 79), Coutts, Freeman, Ebanks-Landell, Duffy.
Unused: Ramsdale, Wright, Riley, Wilson, Reed.
Gillingham: Nelson, Jackson, Herd (Osadebe 45), Ehmer, Oshilaja, Wagstaff, Hessenthaler (Byrne 84), McDonald, List (Donnelly 56), Dack, Wright.
Unused: Knott, Hadler, Dickenson, Emmanuel-Thomas.