Brighton's Welbeck dents Liverpool's Champions League hopes
Arne Slot's men travelled to the sunny south coast in buoyant mood after hammering Galatasaray 4-0 in midweek to reach the Champions League quarter-finals.
But a goal in each half from the evergreen Welbeck gave the home team a fourth win in five Premier League matches, keeping alive their own hopes of European football next season.
The loss was a 10th defeat of a feeble Premier League title defence from Liverpool, which has raised serious questions over Slot's future at Anfield.
The visitors, missing goalkeeper Alisson Becker and forward Mohamed Salah, suffered a further injury blow when topscorer Hugo Ekitike hobbled off early with an apparent dead leg.
Liverpool boss Slot said losing the France forward was a major setback, given his current lack of forward options.
"There is always pressure at Liverpool, on me, on the players -- that is completely normal," the Dutchman told TNT Sports when asked about the need to end the season on a high.
"We have qualified for the quarter-finals of the FA Cup and the Champions League but in the league we need to make sure that in the end, we qualify for the Champions League."
He added: "There are other games where we should have picked up more points, like last week against Tottenham (a 1-1 draw). That is far more unacceptable than this."
Welbeck double
The champions found themselves behind courtesy of Welbeck's 11th Premier League goal of the season in the 14th minute.
The England international nodded home from close range after Diego Gomez headed Ferdi Kadioglu's cross-field pass back across goal, becoming the top English goalscorer in the league this season.
Liverpool found some rhythm and were level in the 30th minute after some clever opportunism from left-back Milos Kerkez.
The Hungary defender capitalised on an error from Brighton captain Lewis Dunk, who headed the ball back to Bart Verbruggen without looking behind him, nipping in and flicking the ball over the stranded goalkeeper.
The home team started the second half brightly and were back in front in the 56th minute, with former Manchester United and Arsenal forward Welbeck scoring his second of the game.
Yankuba Minteh's pinpoint cross was played into Welbeck's path by Jack Hinshelwood and he finished confidently, with the goal confirmed following a VAR check.
Welbeck, who made his Premier League debut for United in 2008, is enjoying his highest-scoring season in the league, though was not included in Thomas Tuchel's latest England squad.
Slot threw on teenager Rio Ngumoha, Andy Robertson and Federico Chiesa in a desperate search for an equaliser but it was Brighton who continued to create the better chances.
Brighton boss Fabian Hurzeler praised his team's work-rate.
"We pressed intense, we played intense, we had good energy on the pitch, we created a lot of chances, especially in the second half," he said.
Defeat leaves Liverpool fifth in the Premier League, two points behind Aston Villa and one ahead of Chelsea, with the top five almost certain to qualify for the Champions League next season.
They are still alive in the Champions League and the FA Cup but face the real prospect of ending the season trophyless, with quarter-finals to come against Paris Saint-Germain and Manchester City.