Striker Andre Onana seals United's home defeat as Spurs suffer yet another defeat at Everton in Premier League football.
Manchester United's season has gone beyond turmoil after a 3-1 home loss to Brighton in the Premier League.
United suffered a miserable defeat after goals from Yankuba Minteh, Kaoru Mitoma and Georginio Rutter at Old Trafford on Sunday handed United a 10th defeat in the league.
Bruno Fernandes scored for United from the penalty spot, but the hosts were not helped by goalkeeper Andre Onana, who spilled a routine header from a low cross into the box, allowing Rutter to to bring home a loose ball.
It was the seventh defeat in a total of 15 games under new head coach Ruben Amorim and highlighted the huge task the Portuguese manager has on his hands to revive the record 20-time English champions. .
Brighton climbed to ninth place with 34 points, four points off the top four. United are 13th on 26, also in 22 games.
Brighton have won six of their last seven league games with United and their last three away to Old Trafford.
The teams were led by a pipe in memory of club great Denis Law, who died this week, with a wreath laid in the center by former manager Alex Ferguson.
Brighton took the lead inside five minutes when Mitoma beat the offside trap to the left of Carlos Baleba's long ball and his pass across goal gave Minteh a simple finish unmarked.
United won a penalty midway through the first half when Brighton tried to play the ball out of defence, but goalkeeper Bart Verbruggen's pass was poor and the ball fell to Joshua Zirkzee in the box.
Baleba put his arm on the shoulder of the attacker, who went to the ground. Referee Peter Bankes pointed to the spot, with Fernandes having no trouble slotting home to level the scores.
Brighton thought they were ahead again seven minutes into the second period when United failed to clear a low free-kick into the box and Pedro finished. But a VAR investigation ruled that Jan Paul van Hecke had kicked Diogo Dalot's leg in the melee.
However, the visitors got a second on the hour when Mitoma stretched at the back post ahead of United defender Noussair Mazraoui to turn in Minteh's inviting cross.
Brighton then bagged a third thanks to Onana's horrendous error to make the game safe and leave United to remain on their 10th league defeat.
Elsewhere, Tottenham Hotspur's dismal campaign also sank to new depths with a 3-2 defeat at relegation-fighting Everton. But Nottingham Forest's unlikely title challenge goes from strength to strength after they won 3-2 against eventual winners Southampton.
