A scrappy goal from Steven Alzate was enough for all three points and left Liverpool seven points behind league leader Manchester City, who have a game in hand.
Liverpool and City face each other on Sunday in what many believed would be an early title decider.
“As this moment stands, we’re not in the title race,” Liverpool full back Andy Robertson told reporters after the game.
Jurgen Klopp’s side, which seemed to have turned the corner after recent good performances, looked short of ideas against Brighton and managed just one shot on target the entire match.
It has now failed to score in three consecutive league games at Anfield, an unimaginable record considering the team’s attacking prowess over the last two seasons.
Robertson credited Brighton as “the better team,” but admitted his own side were “hugely disappointing.”
“We didn’t really do anything of note,” he said. “With a long record of going unbeaten, we’ve lost two. When you don’t show up, you don’t get results.”
The loss further highlighted the vulnerabilities of a side that many thought could go on to dominate English football for years to come.
Klopp has had to deal with injuries to key players, including almost all of his senior central defender options, which has made navigating a congested fixture list difficult, especially during a global pandemic.
“The only explanation now is that we are a fatigued team, mentally more or less,” he told reporters after the match. “We looked mentally not fresh. They deserved to win.”
“We wanted to play better and more convincing. We lost too many balls in promising situations. I know the boys can play pass A to B but today B did not seem reachable.
“We had a really tough week. We were not fresh tonight and that’s when you have to find a way.”
‘The more you win, the better you feel’
Liverpool’s loss will have added an extra gloss to Manchester City’s night, which moved further clear at the top of the league after beating Burnley 2-0 on Wednesday.
Goals by Gabriel Jesus and captain of the night Raheem Sterling secured a comfortable victory which stretched the team’s winning run to 13 games in all competitions.
Sterling credited the “togetherness” of the squad and the key defensive work that has given them a sixth consecutive clean sheet, equaling a club record.
“The more you win, the better you feel, and that’s what we’ve done today,” he told reporters after the match.
“We knew exactly what they would bring to the game being physical, second balls and putting balls in the box, and I thought the boys at the back dealt with them really well.
“It’s good to get another win and keep another clean sheet. We’ve been on a good run and we need to continue that now.”
While pleased with the performance, City manager Pep Guardiola looked ahead to the clash with Liverpool and noted the importance of recovery in a busy schedule.
“Right now, we enjoy this game and tomorrow we start to think about the next game,” he said.
“It is the same points but against a contender. At the end, the aim is to be champion. Against teams lower in the table, people can say it’s guaranteed but we know how difficult it is.
“We had to do our best and now we face a different team with a different type of play. Now come another tough, tough group of games. Today, we enjoy the game, have good food, and tomorrow, we start to think about Liverpool.”