SOUTHAMPTON -- Jurgen Klopp stressed the importance of Roberto Firmino and Mohamed Salah to Liverpool and praised their workrate in the 2-0 victory at Southampton on Sunday.

Liverpool moved up to third in the Premier League, two points adrift of second-placed Manchester United, following a comfortable win on the south coast.

Firmino scored his 20th goal of the season inside six minutes at St. Mary's and delivered an exquisite backheeled assist for Salah's 42nd-minute goal, the Egypt international's 29th in all competitions.

"Our boys are important for us," Klopp told his postmatch news conference. "What I love is of course their skills and attitude, but the workrate is outstanding.

"Both get the profit from the style of play, that's for sure as well. We play in the areas where they like to have the ball.

"In this strong league you cannot be third without fantastic players and yes, they are two of them."

Of the battle for second place, Klopp said: "We don't hesitate, we take whatever we can get but it's not that we make the final bill now.

Mohamed Salah scored his 29th goal in all competitions for Liverpool on Sunday. Michael Regan/Getty Images

"We didn't know before the game that United would lose, but we know that we are not too far away. But it's not a battle between them and us, we play against them one more time in this season at least.

"For us, 54 points, that's important. What the other teams have we have no influence on, so we need to win. We now have the Champions League, then we have West Ham at home, which is difficult.

"That's all exciting, all intense, we need all the points and for today I am really happy that we could take these three."

Virgil van Dijk earned his first Premier League win as a Liverpool player, recording his first clean sheet since joining from Southampton at the start of January.

The world's most expensive defender was given a hostile reception by the home crowd at St. Mary's on Sunday as he returned to his former club for the first time since his £75m move.

"He did really well, he dealt with the situation fantastically," Klopp said. "We had a little talk before the game and I asked: 'What do you think?'

"He said: 'No, I'm fine boss.' I don't want to make him nervous if he isn't nervous and, obviously, he wasn't and that's good.

"I understand everything in football; the crowd is there to make life difficult for the opponent but I think it was not too difficult for him from this point of view and I'm happy about it."

Struggling Southampton end the weekend back in the bottom three after their defeat followed wins for relegation rivals Swansea, Newcastle and Huddersfield.

There were boos from the home crowd at the full-time whistle, while manager Mauricio Pellegrino was also jeered for some of his tactical decisions during the game.

The Saints boss empathised with the supporters and feels they need unity to climb out of their perilous position.

"It's really difficult to ask for more support than this in this situation,'' the Argentine said.

"I have to be grateful with the fans for respecting the players until the end.

"We have the same feelings right now. We are responsible for this. I am the first responsible for this.

"Southampton, we are together. But this is the competition. The competition, sometimes you are in a difficult situation.''

Saints did have chances to level at 1-1 with Pierre-Emile Hojbjerg and James Ward-Prowse each denied by Liverpool goalkeeper Loris Karius, but they struggled to respond in a disappointing second period.

Asked if there was a lack of character in his squad, Pellegrino replied: "Obviously we are not happy with that, but my players are conscious that three points will change everything every single week.

"We have the capacity to try and fight. Everything is really tight.

"The team that is calm in the concept, brave in character and focused, is the team with more weapons to go up (the table).''

Press Association contributed to this report