Slot opened by highlighting Salah's professionalism after the forward completed 90 minutes in his first start since November. The Egypt international had only returned to Liverpool training earlier in the week following Africa Cup of Nations duty but showed no signs of rust in France.
"It helps that he's been with us for so long and knows his team-mates," Slot said. "It says a lot about how professional he is that he's been away for a month with a different team and can play 90 minutes like that. He was close to scoring and usually that's a goal for him, but it didn't harm us because we scored three."
Goals from Dominik Szoboszlai, Geronimo Rulli (own goal) and Cody Gakpo secured a comfortable night at a difficult venue, with Slot stressing how important control and patience were against Marseille.
"It's always hard to play here because of the fans, the quality of their players and the quality of their manager," he said. "We were well prepared. The difference was being clinical. We didn't create many chances, but we scored three."
Slot also made a point of praising Joe Gomez, who has struggled for consistent minutes in recent seasons.
"The one I really want to point out is Joe Gomez," Slot added. "He hasn't played a lot in the last one-and-a-half years, sometimes because of injuries, sometimes because of my choices. Tonight he was great."
Liverpool's win moved them up to fourth in the Champions League table and extended their unbeaten run across all competitions. Attention now turns back to domestic action, with Slot's side travelling to Bournemouth on Saturday for a 17h30 Premier League kick-off.
Thomas Frank expects a tough afternoon for Tottenham Hotspur as his side prepare to face Burnley at Turf Moor on Saturday, warning that Scott Parker's team remained a serious threat on home soil.
Harry Kane continues to set the pace for Bayern Munich this season, with the England captain driving the club's charge at the top of the Bundesliga through goals, leadership and consistency.
Pep Guardiola launched a fierce defence of Manchester City after a damaging run of results, insisting an "unsustainable" injury crisis lay at the heart of their recent struggles.
Arne Slot has said Milos Kerkez is getting "stronger and stronger" as the Liverpool left-back continues to settle into life at Anfield ahead of a Premier League trip to his former club Bournemouth.
