Teenage winger Bukayo Saka scored his first goal for Arsenal as they beat 10-man Eintracht Frankfurt 3-0 in the first round of Europa League group matches on Thursday.
Dynamo Kiev and FC Copenhagen scored 1-0 wins over Malmo and Lugano respectively in Group B while Cluj of Romania beat Lazio 2-1 and Rennes and Celtic played out a 1-1 draw in Group E.
Joe Willock put Arsenal ahead in the first half with a deflected shot that flew in off the underside of the crossbar, but Frankfurt battled gamely until midfielder Dominik Kohr was sent off for picking up two yellow cards in the second half.
Londoner Saka, 18, added a second with a superb curling shot in the 85th minute and Pierre-Emerick Aubameyang slotted home a third to secure all three points for the Premier League side in the Group F clash in Germany.
The win put Arsenal top of the group ahead of Standard Liege who beat Vitoria Guimares of Portugal 2-0 at home.
Apoel Nicosia came back from two goals down to lead 3-2 against Dudelange of Luxembourg, but goals by Dominik Stolz and Daniel Sinizi gave the visitors a 4-3 win in Group A. Qarabag slumped to a 3-0 home defeat by Sevilla in the group's other game.
Winger Kevin Bua scored twice for Swiss side FC Basel as they got off to the perfect start in Group C by hammering Krasnodar 5-0 at home. Getafe beat Trabzonspor 1-0 in the group's other game.
In Group E, Norwegian side Rosenborg fell to a 1-0 defeat at Austrian side LASK and Dutch club PSV Eindhoven edged out Portugal's Sporting Lisbon 2-1.
Manchester United host Kazakhstan's Astana among the later kick-offs.