Arsenal won 4–0 over PSV Eindhoven in their first Champions League game since the 2016/17 season.
Bukayo Saka, Leandro Trossard and Gabriel Jesus all scored in the first half amid rain in London and Martin Odegaard equalized after the break.
“It was a beautiful night after such a long time. The atmosphere, the music of the Champions League was great to see. It was emotional before the game, Arsenal manager Mikel Arteta said.
Their Group B rivals Sevilla and Lens drew 1-1 in Spain, with Angelo Fulgini’s free-kick giving the French side the equalizer after Lucas Ocampos had put the hosts ahead.
Last season’s defeated finalists Inter Milan needed Lautaro Martínez’s 87th-minute equalizer to draw 1-1 at Real Sociedad in Group D.