The Blades entered the clash unbeaten in their previous seven league meetings with Brighton, and worked the first opening of the game when Jayden Bogle’s shot was parried to safety by Bart Verbruggen.
Simon Adingra was looking to cause problems down the right flank on his return from Africa Cup of Nations glory with the Ivory Coast, as Anel Ahmedhodzic almost diverted his cross into the net for an own goal until the Bosnian’s blushes were saved by Wes Foderingham.
Chris Wilder would have been hoping to see his side contain the Seagulls, but those best-laid plans were torn to shreds following Mason Holgate’s moment of madness.
The Everton loanee caught Kaoru Mitoma with a horrendous tackle, which was upgraded from yellow to red following a VAR review.
An uphill struggle became that much steeper when Facundo Buonanotte scored his third PL goal of the season, diverting the ball home from close range after Lewis Dunk headed a Pascal Gross corner back across the six-yard box.
Danny Welbeck then added a second for Roberto De Zerbi’s side, with the Englishman first to respond after Foderingham saved Mitoma’s initial effort from another Gross delivery.
Wilder’s team were still in this match heading past the hour mark, with the Seagulls turning to Evan Ferguson in a bid to kill off this contest as the Irishman replaced Buonanotte.
The 19-year-old was aiming to end a barren run of 14 consecutive games in all competitions without a goal, and almost made an immediate impact when he headed a Gross corner at Foderingham.
Any slim hopes of a Sheffield United comeback were extinguished when Jack Robinson prodded in Mitoma’s cross for an own goal on his 300th career appearance.
Adingra added a well-deserved fourth with a sublime first-time finish from another Gross delivery, and scored a second when his deflected drive beat Foderingham late on.
This result ended a frustrating run of six PL away games without a victory for De Zerbi’s men, who moved up to seventh in the table, leapfrogging both Newcastle and West Ham, as both clubs dropped points the previous day.
Meanwhile, this result for the Blades means they are now winless in their opening four competitive home fixtures of a calendar year for the first time since 2011, and continue to prop up the table with a measly 13 points from 25 games.
Flashscore Man of the Match: Pascal Gross (Brighton)
