Copenhagen were outplayed by Celtic but the latter had Fraser Forster to thank for earning them a first-leg draw with a penalty save.
Police have charged and reported a boy following the alleged racist abuse of a Rangers player in a December match against Celtic.
Barcelona revealed two signings on deadline day, Atletico brought in a familiar face, while Juventus' Emre Can moved to Borussia Dortmund.
After making a limited impact at Norwich City, Manchester City-owned Patrick Roberts has joined Middlesbrough on loan.
Repeated controversial decisions against Rangers and Alfredo Morelos have prompted a response from the Old Firm winners.
Alfredo Morelos was sent off for the seventh time in his Rangers career but Nikola Katic's header secured victory over Celtic.
There were more favourable opponents on paper than Club Brugge and Olympiacos for Manchester United and Arsenal in the Europa League.
Manchester United have a tricky tie against Club Brugge in the next round of the Europa League, while Inter go to Bulgaria's Ludogorets.
Karamoko Dembele and Scott Robertson each impressed Neil Lennon on their European bows for Celtic
Celtic put in an underwhelming display in Romania as Cluj secured their place in the Europa League knockout stage with a 2-0 triumph.