But a late goal from substitute Danny Welbeck held the luckless Blades to a 1-1 draw.
Both sides struggled to get into a rhythm in the opening half hour with Aaron Connolly scuffed effort and David McGoldrick’s clever free kick the only real chances.
But a slow burner of a tie drifting to half time, Chris Wilder’s task was made even harder as John Lundstram was sent off for a lunge at Joel Veltman.
United were forced to dig in after restart before Jadon Bogle buried his first Blades goal on the hour.
McGoldrick did brilliantly to hold the ball up and slip in the former Derby man to smash past Robert Sanchez.
The Seagulls were swift in their response with Adam Webster bringing the best from Aaron Ramsdale and Connolly headed a gift-wrapped chance over the bar.
But with all the pressure being applied the Blades goal, they eventually cracked with five minutes left, as Welbeck sharply turned home a loose ball.
Brighton substitute Alireza Jahanbakhsh did almost net a bizarre own goal in added time but the Blades bad luck struck once again.
Full Time at the AMEX Stadium it’s Brighton 1 Sheffield United 1