Arsenal will take on Sporting Lisbon in the group stage of the Europa League.
The Gunners, last season's semi-finalists, were drawn in Group E alongside the Portuguese club, Azerbaijan champions Qarabag and Ukrainian outfit Vorskla.
Portuguese club Sporting have started their domestic campaign unbeaten despite a troublesome summer that saw seven players cancel their contracts following an attack by fans at the training ground last season.
Arsenal boss Unai Emery has won the competition three times as manager of Sevilla.
Chelsea face some long trips on their return to Europe's second-tier competition for the first time since they lifted the trophy in 2013.
Maurizio Sarri's Blues have been drawn with Greek side PAOK, Belarusian champions BATE Borisov and Hungarian title winners Vidi in Group L.
Scottish giants Celtic and Rangers both face difficult draws as they aim to negotiate the group stages.
The official result of the #UELdraw! 🤩
Toughest group? 🤔 pic.twitter.com/nfTeWdG1rq— UEFA Europa League (@EuropaLeague) August 31, 2018
Celtic are in Group B with Austrian champions Red Bull Salzburg, Bundesliga side RB Leipzig and Norwegian title holders Rosenborg, who the Celts beat in a Champions League qualifier this summer.
Rangers are back in a European group stage for the first time since the 2010-11 Champions League following their play-off win against Ufa.
They will return to Russia to face Spartak Moscow in Group G, which also contains LaLiga side Villarreal and Austrian's Rapid Vienna.
The final of this season's Europa League takes place in Baku on May 29.