Former European Cup winners Red Star Belgrade have reached the Champions League group stage for the second successive season.
The Serbian team advanced on away goals after drawing their play-off second leg 1-1 at home with Swiss side Young Boys. The scores were level at 3-3.
Croatian champions Dinamo Zagreb are also through after beating Rosenborg 3-1 on aggregate following a 1-1 draw in the second-leg and a 2-0 win in the first leg.
Meanwhile, Olympiakos won 2-1 at Krasnodar to complete a 6-1 aggregate victory against the Russian side.