Former European Cup winners Red Star Belgrade reached the Champions League group stage for the second successive season after a 1-1 home draw with Young Boys sent them through on away goals on Tuesday.
They were joined by Croatian champions Dinamo Zagreb who advanced with a 1-1 draw at Rosenborg following a 2-0 first-leg win. Olympiakos won 2-1 at Krasnodar to complete a 6-1 aggregate drubbing of the Russian side.
Roared on by a fervent 50,000 home crowd, 1991 European champions Red Star, who earned a 2-2 draw in the reverse fixture, were on the back foot for an hour and rode their luck at times before winger Aleksa Vukanovic fired them ahead.
Left back Milan Rodic missed Red Star's best chance in the first half when he headed over the bar before midfielder Michel Aebischer twice went close to swinging the tie Young Boys' way.
Red Star keeper Milan Borjan almost spilled a deflected cross into his own net and then saved a Roger Assale sitter before the home side broke the deadlock with their first purposeful move of the night.
Playmaker Marko Marin released Rodic with a delightful pass and the left back raced down the flank to deliver a sharp cross for Vukanovic to head home from six metres at the near post.
The Serbian champions endured a tense last 10 minutes after they half-cleared a deep cross into their penalty area and substitute El Fardou Ben turned a Saidy Janko shot from 18 metres into his own net.
Dinamo fell behind on the night to an early Babajide David goal before Amer Gojak struck in the 71st minute to put the tie beyond the Norwegian side's reach.
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Olympiakos arrived in Krasnodar with a 4-0 first-leg cushion and although the Russian side gave themselves a glimmer of hope through Daniil Utkin's 10th-minute effort, Youssef El Aarabi scored twice for the visitors to book their group-stage berth.
Last season's semifinalists Ajax Amsterdam are at home to APOEL Nicosia in Wednesday's standout fixture following a 0-0 first-leg draw in Cyprus.
Brugge are at home to LASK Linz following a 1-0 win in Austria and Slavia Prague host Romanians CFR Cluj after beating them by the same score last week.