United remain firmly in the play-off race, despite seeing the momentum halted by Millwall at Bramall Lane.
Leon Clarke's 18th of the season appeared to have set the Blades on course for a crucial three points, but Steve Morison's reply for the Lions denied the Blades the opportunity to crank up the pressure on the teams above.
For the lunchtime encounter with the Lions, Blackman and Stearman returned, with Moore and Wright both dropping to the bench.
The atmosphere was electric at kick-off and Evans almost picked up from where he'd left off against Middlesbrough, but his curling effort went inches wide, with Archer beaten. Fleck was the next to try his luck following a poor throw out by Archer, but the goalkeeper made amends with a comfortable save.
In the 22nd minute, Millwall had their first chance of note, Hutchinson found himself in space at the back post from Marshall's deep corner, but Blackman claimed the ball at the second attempt, under pressure from Gregory. At the other end, Cooper's end took the ball away from Stevens, before Lundstram headed over in the second phase.
United continued to shade proceedings, with Clarke dragging an effort wide with angle against him and moments later Fleck was denied by Archer, after capitalising on some hesitation in the Millwall midfield. The visitors were presenting a threat from set-pieces, with Cooper and then Wallace denied by timely blocks.
In the final minute of the first-half, Williams was the first to be carded by referee Coote for pulling down the advancing Lundstram. And the final action of the half, saw Archer deny Stearman at the expense of a corner, where Basham was unable to deflect Clarke's header at goal.
At the break, Duffy replaced Lundstram, but it was the visitors who almost opened the scoring at the beginning of the second period, but Gregory was unable to score after latching onto to Duffy's short back pass. In response, Baldock forced a spectacular save from Archer from O'Connell's inviting left-wing cross.
Just before the hour, Sharp was introduced in place of Brooks. But it Blackman who United needed to call upon moments later, with the goalkeeper saving excellent to deny Williams with a header from Marshall's corner.
Stearman was booked for a foul on Morison and subsequently replaced by Lafferty, as Wilder changed the formation. Duffy then broke free of Romeo, but his effort went wide of Archer's post. But in the 75th minute the Lane erupted as United went in front. Evans whipped in a ball to the back post and from O'Connell's header across goal CLARKE was jogging on the spot to apply the finish.
But the Lions hit back more or less straight from kick-off to restore parity. Cooper's punt forward fell perfectly for MORISON to divert to ball past an advancing Blackman. Saville was booked, as was Marshall as tempers became fraught. Millwall continued to cause problems from corners, with Baldock almost diverting Morison's header past Blackman.
Back at the other end, Baldcock's cross saw Archer save from Sharp and Clarke was unable to force home the rebound. Spurred on by the Kop, Duffy's effort looked goalbound only for Hutchinson, who had earlier volleyed over at the other end, make a crucial block.
Four minutes of added time were signalled and the Kop thought referee Coote had awarded the Blades a penalty, only for him to book Evans for an apparent dive and that proved the last action of note as the spoils were shared.
Blades: Blackman, Baldock, Stevens, Fleck, O'Connell, Basham, Lundstram (Duffy 45), Clarke, Stearman (Lafferty 71), L Evans, Brooks (Sharp 59).
Unused: Moore, Donaldson, Wright, Leonard.
Millwall: Archer, Meredith, Hutchison, Williams, Gregory (Elliott 90), Romeo, Wallace, Morison, Saville, Cooper, Marshall (Onyedinma 84).
Unused: Cahill, Martin, Tunnicliffe, O'Brien, Shackell.