Forest secured a 3-0 win at Fenerbahçe in Vítor Pereira's first game in charge, while Stuttgart overwhelmed Celtic at Parkhead. Both English sides will be favored to advance when they host the second legs at their home venues.
Meanwhile, Genk leads Dinamo Zagreb 3-1, Bologna holds a 1-0 advantage over Brann, and Celta is 2-1 up against PAOK. In the Conference League, Crystal Palace must overturn a 1-1 draw with Zrinjski Mostar.