Barcelona maintained their perfect start to the Champions League campaign with an emphatic 4-1 comeback victory over Galatasaray at RAMS Park, while Bayern Munich were forced to settle for a dramatic 3-3 draw against Viking in Stavanger.
The two matches delivered contrasting nights for the European heavyweights, with Barcelona recovering from an early setback to dominate in Istanbul and Bayern fighting back from two goals down before conceding a late equaliser in Norway.
Galatasaray stunned Barcelona in the 28th minute when Rafael Leao raced down the left before cutting the ball back for Aleksey Batrakov, whose deflected effort beat Joan Garcia to give the Turkish champions the lead.
The hosts thought they had doubled their advantage shortly afterwards when Baris Alper Yilmaz converted from close range, but VAR ruled the goal out for offside.
Barcelona took full advantage of the reprieve and levelled two minutes before half-time. Dani Olmo kept an attack alive with a well-timed challenge before Joao Cancelo calmly finished beyond Ugurcan Cakir to make it 1-1.
Hansi Flick's side then took complete control after the interval.
Lamine Yamal created Barcelona's second goal in the 50th minute, delivering a cross that Fermin Lopez headed home from close range to complete the turnaround.
Yamal was involved again just three minutes later, beating his marker near the byline before finding Anthony Gordon, who finished from a tight angle to give Barcelona a 3-1 advantage.
Substitute Karim Adeyemi completed the scoring in the 65th minute, drilling a low effort beyond Cakir after another Barcelona attack developed through Yamal and Gabriel Jesus.
The victory gave Barcelona six points from their opening two Champions League matches and extended their perfect start across all competitions.
There was far greater drama in Stavanger, where Viking produced a remarkable performance to hold Bayern Munich 3-3.
The Norwegian side made a dream start when Gianni Stensness headed home Zlatko Tripic's corner after just 71 seconds, stunning the German visitors.
Peter Christiansen then doubled Viking's advantage in the 38th minute. Erik Botheim released the winger on the counter-attack and Christiansen raced clear before finishing calmly to send the hosts into half-time with a 2-0 lead.
Bayern responded immediately after the break.
Harry Kane reduced the deficit from the penalty spot in the 54th minute after VAR determined that Konrad Laimer had been fouled inside the area.
Kane struck again six minutes later, heading Joshua Kimmich's cross beyond Arild Ostbo to bring Bayern level at 2-2.
The comeback appeared complete when Luis Diaz finished a flowing move in the 71st minute. Kane's clipped pass released Laimer, who crossed for Diaz to convert and put Bayern 3-2 ahead.
Momentum shifted again shortly afterwards when Michael Olise received two quick yellow cards, the second coming after he threw the ball into Tripic's face, leaving Bayern with 10 men.
Viking refused to surrender and were rewarded in the 90th minute.
Tripic drove down the left and delivered a cross towards the back post, where Herman Haugen rose to head past Jonas Urbig and secure a memorable 3-3 draw.
The result left Bayern to reflect on dropped points despite recovering from a two-goal deficit, while Viking celebrated a famous result against one of European football's biggest clubs.
It was a night that underlined the unpredictability of the Champions League, with Barcelona displaying their attacking strength in Istanbul while Viking demonstrated remarkable resilience to deny Bayern a dramatic comeback victory.
