Arsenal earned their first win of this season’s Champions League, with a 2-0 win over Paris Saint-Germain on Tuesday night.
The Gunners had drawn 0-0 with Atalanta on Match Day 1.
But back at the Emirates, goals from Kai Havertz and Bukayo Saka gave the hosts a crucial victory.
Manchester City also recorded their first win, with a commanding 4-0 win at Slovan Bratislava.
Dortmund hammered Celtic 7-1 and Brest won 4-0 at RB Salzburg.
In other results, Barcelona crushed Young Boys 5-0 and Inter Milan claimed a 4-0 home win over Red Star Belgrade.
Victor Boniface scored the only goal as Bayer Leverkusen beat AC Milan 1-0.