Reece James and Enzo Fernandez netted in the second half, before Gabriel Pereira halved the deficit for the hosts, as Enzo Maresca's side just did enough to take control of the tie in the Danish capital.

Following an uninspiring opening period, Chelsea skipper James broke the deadlock one minute after half-time when he strode onto Marc Cucurella's deep cut-back and rolled an effort from distance inside the near post.

The goal brought the game to life and Copenhagen nearly struck back instantly, only for Viktor Claesson to see his one-on-one effort come back off the inside of Robert Sanchez's post and into the goalkeeper's grateful arms.

Half-time substitute Fernandez made the game safe for the visitors with an emphatic 65th-minute finish following good work by teenager Tyrique George.

The Premier League side were cruising until 11 minutes from time when Pereira was left unmarked in the box to nod in from a set-piece.

Elsewhere, last season's defeated finalists Fiorentina went down 3-2 to Greece's Panathinaikos.

The Greek hosts flew out of the traps, racing into a 2-0 lead inside 19 minutes courtesy of Karol Swiderski and Nemanja Maksimovic.

But within just four minutes, Fiorentina were back level after two rapid-fire strikes from Lucas Beltran and Nicolo Fagioli.

Tete restored the hosts' lead ahead of the second leg with a sweeping, left-footed finish in the 55th minute.

Molde held on to win by the same scoreline against Legia Warsaw in Norway.

Eirik Hestad scored a neat opener on 11 minutes, before Kristian Eriksen doubled up six minutes later.

Fredrik Gulbrandsen raced onto a fine through ball from Emil Breivik to add a third shortly before the interval.

Kacper Chodyna and Luquinhas scored two in three second-half minutes to drag the Poles back into the tie.

La Liga club Real Betis drew 2-2 at home to Iberian neighbours Vitoria Guimaraes of Portugal.

After a goalless first period, Cedric Bakambu nudged the Andalusians in front in the 48th minute, before Joao Saraiva levelled three minutes later.

Former Real Madrid star Isco looked to have grabbed the winner for Betis with 15 minutes remaining but Vitoria hit back through Nelson Oliveira inside the final 10 minutes.

Later, Austria's Rapid Vienna visit Borac Banja Luka of Bosnia and Herzegovina, and Swiss side Lugano are hosted by Slovenes Celje.