The result has heaped the pressure on Magpies boss Steve Bruce with fans demanding managerial change at St James’s Park.
But Bruce has vowed to fight on at Newcastle United after an abject defeat for his team at the Amex Stadium.
The club has won just two out of its last 20 games in all competitions – and the position of United's head coach looks to be untenable.
Asked what the defeat meant for his position at the club, Bruce said: “Well, as I’ve always said, that’s for other people to answer, but the one thing that I won’t ever do is give up on anything, as we’ve had a bad defeat.
We’ve been OK, I believe, we haven’t been sensational over the last few weeks, but we have to accept, I have to accept, the criticism that’s going to come our way and the fallout from it, because we were simply nowhere near good enough on a big occasion. We simply haven’t done enough.
"Of course, the buck stops with me. It always does, and I have no problem (with that), because of the way we played, I fully understand the frustration and disappointment of everybody, and rightly so.”
Here, the Gazette’s chief Newcastle United writer Miles Starforth delivers his player ratings after watching the game at the Amex Stadium:
. BRIGHTON, ENGLAND - MARCH 20: Neal Maupay of Brighton & Hove Albion scores their team's third goal during the Premier League match between Brighton & Hove Albion and Newcastle United at American Express Community Stadium on March 20, 2021 in Brighton, England. Sporting stadiums around the UK remain under strict restrictions due to the Coronavirus Pandemic as Government social distancing laws prohibit fans inside venues resulting in games being played behind closed doors. (Photo by Clive Rose/Getty Images)
Neal Maupay of Brighton & Hove Albion scores their team's third goal during the Premier League match between Brighton & Hove Albion and Newcastle United. Photo: Clive Rose
. Martin Dubravka - 5
Had a nervous start, and needed treatment at one point, let down by those in front of him Photo: Mike Hewitt
. Javier Manquillo - 4
Recalled to the starting XI after recovering from an ankle problem, stood off Wellbeck for the second goal Photo: Clive Rose
1. Martin Dubravka - 5
Had a nervous start, and needed treatment at one point, let down by those in front of him Photo: Mike Hewitt
2. Javier Manquillo - 4
Recalled to the starting XI after recovering from an ankle problem, stood off Wellbeck for the second goal Photo: Clive Rose
3. Jamaal Lascelles - 5
Could only do so much to keep Brighton at bay Photo: Clive Rose
4. Ciaran Clark - 4
Turned for Trossard’s goal, nowhere near his best on an awful night for United Photo: Mike Hewitt