Keith Treacy's first United goal rescued a point and maintained the unbeaten start to the Championship season.
The on-loan winger's impressive strike - also his first ever league goal - cancelled out a deflected effort from Matty Fryatt.
More than 26,000 supporters were inside Bramall Lane to see a high-energy encounter in which both sides had their spells of possession.
Saturday's impressive victory over Watford prompted Blackwell to name an unchanged team for the home clash. United's only change was on the bench, where Sharp replaced Little. It took less than two minutes for the home side to hurl in a long throw and win a corner, whilst the formation, expectedly, was similar to the weekend.
The early action was frantic and lacked a little composure but Leicester, to their credit, looked to go forward and Taylor picked up a booking on eight minutes for his block on N'Guessan. The visiting side's aerial threat, however, was hampered soon after when Howard limped off, holding his hamstring.
Fryatt's shot, on 14 minutes, was saved and gathered at the second attempt by Bunn, whilst the same duo were in action again soon after when the goalkeeper raced off his line bidding to cut the striker's angle but Kilgallon was needed to hack clear.
Good opportunities were then exchanged within the space of 60 seconds. Ward, Evans and Henderson linked up with the latter's shot deflecting off a defender and onto the crossbar before Oakley's threaded through ball put Fryatt clear, only for Bunn to again charge off his line to save with his body.
The frenetic action continued through the half hour mark and Taylor almost caused problems for himself when trying to turn in his own box, whilst Fryatt hoofed well over from a right-wing corner as Leicester continued to push the Blades back.
Wellens was booked for a foul on Ward and Taylor's busy half continued when he was off target with a 30 yard shot before being treated for a head injury.
Howard was added to the bookings list just before the break for a challenge from behind and the frustrating half was brought to an end after two additional minutes, with the scores still level. It was the midfielder's last contribution as he was replaced by Quinn at the break.
United appeared to make a good start to the second half - a Ward shot was parried away by Weale - before Leicester grabbed the lead on 52 minutes. Oakley's 30-yard free-kick, from a central position, was deflected sufficiently beyond Bunn's dive by FRYATT.
Fryatt's next contribution was a booking, for blocking Walker's attempted quick throw, but Leicester's attacking impetus continued. Another long-ranger by Oakley flew through a crowded penalty area but Bunn saved well and then Taylor got back to make a timely tackle on Fryatt.
Taylor was involved yet again soon after, taking a positive role in United's equaliser. He powered down the left and laid off for TREACY to cut inside and before unleashing an unstoppable 25-yarder with his unfavoured right foot. Weale, at full stretch, was well beaten. Just like Fryatt at the other end, Treacy's next act was to pick up a booking!
The goal sparked life into United, attacking the Kop end. Oakley was booked for a foul on Ward and from the resulting free-kick, Quinn's curler was touched over the crossbar by Weale. The Blades substitute fired another effort in soon after, this time his 30-yarder was narrowly wide.
The last 15 minutes opened with Walker getting to the byline and putting in two crosses which caused problems and United were finally getting on top. Cotterill was added for the closing minutes, with Ward tiring, and the replacement was involved in the move which resulted in Montgomery firing over.
Four minutes of added time buoyed the Blades more than the visitors but all that the home side could muster was a mis-hit shot from Evans and a Cotterill cross, which was cleared, before the final whistle signalled a point for both sides.
Blades: Bunn, Montgomery, Morgan, Kilgallon, Henderson, Evans, Taylor, Ward (Cotterill 88), Howard (Quinn 45), Treacy (Reid 73), Walker.
Unused: France, Bennett, Bromby, Sharp.
Leicester: Weale, Neilson, Brown, Oakley, Howard (Waghorn 11, King 83), Fryatt, Berner, Adams (Dyer 78), N'Guessan, Wellens, Hobbs.
Unused: Morrison, Tunchev, Logan, Dickov.
