PSV Eindhoven routed Italian champions Napoli 6-2, while Arsenal and Inter Milan had big Tuesday night wins to maintain their perfect starts in Europe.
But it is defending champions PSG that lead the way after a wild 7-2 win against Bayer Leverkusen in a match that saw both teams reduced to 10 men.
"That's three games, three wins, and crucially we're at the top of the UEFA Champions League table," French forward Ousmane Dembele said.
"We've started this campaign really well, especially considering how difficult it was last season."
Premier League leaders Arsenal beat Atletico Madrid 4-0, with Viktor Gyokeres scoring twice, and last season's finalists Inter beat Union Saint-Gilloise by the same score.
"I am delighted (for Gyokeres) as he fully deserves it," Gunners coach Mikel Arteta said of the Sweden striker, who had gone nine games for club and country without a goal.
"The work rate he brings to the team is outstanding. We value a lot of things that he does for the team and it was the biggest smile on his face today."
Fermin Lopez scored a hat-trick, Marcus Rashford hit two goals with Lamine Yamal also on the scoresheet from the penalty spot as hosts Barcelona thrashed 10-man Olympiacos 6-1.
Haaland's goal, his 24th in 14 games for club and country this season, helped 2022/23 winners Manchester City to a 2-0 win at Villarreal.
The Norway international now has 53 goals in 51 career games in the Champions League and has scored in nine straight games for City in all competitions.
Pep Guardiola's side sit fifth on seven points, level with a Borussia Dortmund side who beat FC Copenhagen 4-2.
"We're happy with a clean sheet and a win," the City manager said.
"We felt in control for most of the game ... but we have to be harsh on ourselves if we want to win the competition."
Elsewhere, Newcastle United beat Benfica 3-0 thanks to a double from substitute Harvey Barnes and Kazakhstani team Kairat Almaty picked up their first point in European soccer's elite club competition with a 0-0 draw against Pafos.
With PA.
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