Edison Cavani opened up the scoring for the hosts in the first minute of play while Alexis Sanchez snatched the draw for the Gunners late in the second.
Also in Group A Swiss side Basel and Bulgarian champs Ludogorets drew by the same scoreline.
Elsewhere Anderson Talisca scored a delightful free kick in stoppage time to help Besiktas to a 1-1 draw with Benfica at the Estadio de Luz in Portugal while Arkadiusz Milik hit a brace of goals to lift Napoli to a 2-1 victory over Dynamo Kyiv in Ukraine.
In two weeks time Besiktas take on Dynamo Kyiv as Napoli face Benfica in the second round of group matches.
In Group C it turned out to be a goal fest at the Camp Nou as five times champions Barcelona thrashed Celtic 7-0 with Lionel Messi scoring a hat-trick on the night. Louis Suarez scored twice while Neymar and Andres Iniesta completed Celtic and boss Brendan Rodgers’ misery.
The match between Manchester City and Borussia Monchengladbach was postponed due to torential rain.
Saul Niguez fired last season’s losing finalists Atletico Madrid to an opening round 1-0 victory over PSV Eindhoven in Group D.
PSV were left ruing a first-half penalty miss by Andres Guardado.
Also in Group D five time European champions Bayern Munich demolished newcomers Rostov 5-0 to give new coach Carlo Ancelotti a winning start in the competition. (Euronews)