Manchester United and Tottenham Hotspur have been handed home starts to their Europa League campaigns, while Rangers will travel to Malmo for their opening match.
FA Cup winners United meet Dutch side Twente on 25 September, with Rangers playing in Sweden on the following day, when Spurs face Qarabag of Azerbaijan.
Rangers' first home match is against Lyon in the following week, on 3 October, when Manchester United visit Porto and Spurs go to Ferencvaros of Hungary.
The Red Devils will also face former United boss Jose Mourinho when they go to Fenerbahce on matchday three, 24 October.
Spurs will head to Ibrox to tackle Rangers in the first all-British tie on matchday six, 12 December, before the Scottish Premiership side go to Old Trafford for matchday seven on 23 January.
The competition has been revamped this year and instead of the recent tradition of the group stage, each team will play eight fixtures in the 'league phase'.
The draw to decide which clubs would face each other was made on Friday, but the match order and kick-off times were only confirmed by Uefa on Saturday.
In the Conference League - where the league phase consists of six matches - Premier League side Chelsea start at home against Belgian team Gent on 3 October while Hearts are away at Dinamo Minsk of Belarus.
Irish League side Larne - the first club from Northern Ireland to qualify for the group or league phase of a major European competition - continue their European adventure with a trip to Norwegian outfit Molde first off.
Welsh history makers The New Saints - the first club from the top-flight Cymru Premier to reach the group phase of a European competition - start with a trip to Serie A giants Fiorentina.