Jose Mourinho's Fenerbahce won 3-0 at home to Anderlecht in the first leg of their Europa League knockout phase play-off tie Thursday, while Real Sociedad triumphed 2-1 away to Midtjylland.
Former Premier League duo Dusan Tadic and Edin Dzeko scored in the first half for Fenerbahce before Morocco international Youssef En-Nesyri headed in a third for the Turkish side to give them full control.
Mourinho won the competition with Porto in 2003 and again with Manchester United in 2017, also reaching the final when he was in charge of Roma two years ago.
Real Sociedad will return to Spain in a commanding position after a penalty from Brais Mendez and terrific goal by Japan winger Takefusa Kubo saw them past Danish Midtjylland, who pulled one back through Adam Buksa.
The winners of the tie will play United or Tottenham in the last 16.
Ajax took charge of their play-off against Belgian outfit Union Saint-Gilloise with a 2-0 victory in Brussels.
Christian Rasmussen steered the Dutch club ahead just before the hour, with 16-year-old Jorthy Mokio volleying in a second from 20 yards.
Israel's Mohammad Abu Fani struck the only goal in Budapest as Ferencvaros won 1-0 against Viktoria Plzen.
Two-time former winners Porto host Roma later on Thursday, while Galatasaray are away to AZ Alkmaar.
In the Uefa Conference League, Irish side Shamrock Rovers secured a 1-0 win away to Norwegians Molde.
Molde defender Valdemar Lund was sent off before halftime for a challenge on Michael Noonan, who netted the winner in the second half to become the competition's youngest scorer at 16 years and 197 days old.
Iceland's Vikingur Reykjavik beat Panathinaikos 2-1 as the Greeks grabbed a vital late goal from the penalty spot.
Celje of Slovenia drew 2-2 against Apoel Nicosia, while Jagiellonia Bialystok captain Jesus Imaz scored twice in a 3-1 win away to Serbia's TSC Backa Topola.