The first round of group stage fixtures for the 2016/17 UEFA Champions League season were played on Wednesday night.
In Group C's rescheduled match, Manchester City easily overcame Borussia Monchengladbach 4-0 at the Etihad Stadium.
Calhanoglu then doubled Leverkusen's lead with a deflected effort from the edge of the area six minutes later.
Bruno Cesar's 47th-minute strike had the Portuguese giants heading for a shock upset at the Santiago Bernabeu before former Sporting star Cristiano Ronaldo came up with a stellar free-kick from range prior to Alvaro Morata's headed winner deep into injury-time.
In Poland, it was a procession as Borussia Dortmund hammered Legia Warsaw 6-0 with six different scorers finding the back of the net, including star striker Pierre-Emerick Aubameyang and summer returnee Mario Gotze.
In the other Group G match, Danish champs FC Copenhagen held Porto 1-1 in Portugal after Andreas Cornelius cancelled out Otavio's early opener.
2016/17 UEFA Champions League - group stage scores
*rescheduled from Tuesday
Legia Warsaw (POL): 0
Borussia Dortmund (GER): 6 (Mario Gotze 7', Sokrates Papastathopoulos 15', Marc Barbar 17', Raphael Guerreiro 51', Gonzalo Castro 76', Pierre-Emerick Aubameyang 87')
Polish Army Stadium, Warsaw, Poland - 27,304