Whoever progresses on aggregate will almost certainly face Manchester United in the quarter-finals of the competition.
While some of the teams at the last-16 stage of this competition are squaring off in one-off ties, Copenhagen and Basaksehir are meeting having already played each other back in March.
A late penalty from Edin Visca has given Basaksehir a narrow advantage ahead of their trip to Denmark, and there will now be a desire to go as far in this competition as possible after claiming their first ever Turkish league title last month.
A return of 16 points from eight matches after the resumption was enough for Okan Buruk's side to finish four points clear of nearest challengers Trabzonspor.
With that success earning Champions League football for next season, the pressure is now off, and Basaksehir will be regarded as a threat if they can avoid defeat on Wednesday evening.
Former Chelsea man Demba Ba found some form during the final weeks of the domestic campaign, contributing three goals from his most recent five appearances.
From Copenhagen's perspective, they head into this contest having surrendered the league crown to FC Midtjylland, finishing as runners-up by a 14-point margin.
While Stale Solbakken witnessed his side win their final two matches, they had previously gone six outings without success.
Although the club legend does not find himself under any immediate pressure, there will be an acknowledgement that he can help his cause with further progression in this competition.
Copenhagen have never reached the last eight of a major European tournament, and there is an argument that they will struggle to ever have a better opportunity to make the next stage.
Copenhagen Europa League form: DWLDWL
Copenhagen form (all competitions): LLDLWW
Istanbul Basaksehir Europa League form: WLWLWW
Istanbul Basaksehir form (all competitions): DWWLWL
Buruk must decide whether to hand a recall to Martin Skrtel, who remained as an unused substitute for the club's final league game.
After being introduced as a replacement, Gael Clichy contributed two assists, which should lead to him coming back into the team.
Solbakken could look to avoid making any significant changes to the team which began the win over Nordsjaelland on July 26.
That would leave Dame N'Doye, who has netted twice in three Europa League appearances, having to settle for a place among the substitutes.
Copenhagen possible starting lineup:
Johnsson; Varela, Papagiannopoulos, Nelsson, Bengtsson; Zeca, Thomsen; Stage, Wind, Daramy; Kaufmann
Istanbul Basaksehir possible starting lineup:
Babacan; Caicara, Topal, Ponck, Clichy; Epureanu, Kahveci; Visca, Aleksic, Crivelli; Ba
We say: Copenhagen 1-2 Istanbul Basaksehir
While Copenhagen usually perform well on home territory, the current restrictions regarding crowds will only play into Basaksehir's favour. With that in mind, we feel that an early away goal will put the visitors on the way to a comfortable night.