Napoli, Celtic, Nice and Villarreal are among the clubs ousted from the Europa League, while RB Leipzig, Lazio and Atletico Madrid are moving on.
The Europa League returned on Thursday night, with European heavyweights Arsenal, Atletico Madrid and Dortmund all vying to protect their current leads and proceed through the round of 32 in their reverse ties.
Here's a round up of the day's early action:
RB Leipzig and Napoli's topsy-turvy match up continued late into the second leg, with Piotr Zielinski cutting the deficit to within one before the interval at 3-2. Lorenzo Insigne leveled the scoring late on and made things tense for the hosts, but the Germans edged the Serie A leaders on away goals.
In France, Nice were hard-pressed to make it through after a late slump to a 3-2 defeat at home to Lokomotiv Moscow last week, after Manuel Fernandes inspired a second half comeback; netting a superb hat trick.
Despite Mario Balotelli hitting the woodwork twice in 20 minutes, Igor Denisov bagged the only goal of the night in the reverse fixture in Moscow, making the aggregate scoreline 4-2 to the home side at full time.
Tournament favorites Atletico Madrid encored last week's 4-1 away victory over FC Copenhagen with another professional display at the Wanda Metropolitano. Kevin Gameiro netted the only goal in the seventh minute, ensuring safe passage to the round of 16 for Diego Simeone's men.
Celtic bowed out of the competition despite having the advantage, after failing to respond to goals from birthday boy Branislav Ivanovic, Daler Kuzyayev and Aleksandr Kokorin at Zenit St Petersburg, as Roberto Mancini's side ran out 3-1 winners on aggregate.
Lazio overturned a one goal deficit emphatically at the Stadio Olimpico scoring five against FC Steaua. Talisman Circo Immobile netted a sensational hat trick, and B. Jactinto Quissanga and Brazilian winger Felipe Anderson added to the score sheet, ending the Romanians' European campaign this term.
Dark horses Lyon progressed to the round of 16 after an uneventful clash against Villarreal at the Estadio de la Ceramica. Bertrand Traore managed to score late on though, securing a simple victory - with the side scoring three at Parc Olympique Lyonnais.
Sporting CP also secured their passage through, despite a poor defensive display in a 3-3 draw against Kazakhstan's FC Astana on the night, having scored three away goals last week.