The Sky Blues went 2-0 up thanks to a Samuel brace but were pegged back at Bramall Lane...
Coventry City left Bramall Lane with only a point after a 2-2 draw with Sheffield United.
A brace from Dominic Samuel gave the Sky Blues a 2-0 lead before two goals in three minutes from Michael Doyle and Jamie Murphy secured a point for the Blades.
The hosts were reduced to ten men after 19 minutes when Jose Baxter lunged in at Adam Barton with two feet near the half-way line and the referee immediately gave the midfielder his marching orders.
City made the man advantage count on the counter attack on 32 minutes, when Jamie Jones hit a wonderful ball up the field to Samuel, who shrugged off a defender and drove into the area, placing a cool finish in for the opener at the near-post.
The Sky Blues continued to look lively on the break and almost made it two when Aaron Phillips hit the top of the net from 20-yards.
But the second came just two minutes after the break when Jim O'Brien and Phillips combined and the defender's cross was met by Samuel who forced a great save from Iain Turner, but finished the rebound superbly from eight-yards.
Adam Barton, who was booked in the first-half, then made way for Jack Finch, with George Thomas coming on for Luke Williams shortly after,
Phillips, who marauded up and down the right side for 90 minutes, went close again with a shot from inside the area which was blocked, before Thomas had a good chance, firing wide from the edge of the box.
United were back in it when Doyle chipped a wonderful effort over Jones in the area on 78 minutes, before the home side scored their second in as many minutes when Murphy fired a shot into the bottom left hand corner from the edge of the area to complete the comeback.
After a late United rally, City secured a point, but will be disappointed not to take all three points.
Coventry City: Jones (GK), Phillips, Pennington, Martin, Stokes (Haynes 72), O'Brien (C), Fleck, Barton (Finch 52), Williams (Thomas 57), Samuel, Tudgay.
Subs: Burge (GK), Webster Jackson, Turgott.
Sheffield United: Turner (GK), Harris, Brayford, Basham, Doyle (C), Murphy, Baxter, Done, Coutts (Freeman 70), McEveley, Campbell-Ryce (Kennedy 45).
Subs: McNulty, Willis, Davies, Reed, Adams.
Attendance: 20,314 (942 away)
Referee: D Drysdale