Manchester City twice took the lead against Real Madrid at the Bernabeu, but couldn't hold onto the lead as they lost 3-2 in a thrilling start to the 2012/13 Champions League.
Meanwhile Arsenal continued their good run of form with a crucial 2-1 win away to French club Montpellier.
City looked Chelsea-esque in Madrid, allowing their gilded hosts to control possession before breaking quickly when Real's attacks broke down.
Joe Hart performed heroics in the first half, keeping the English giants in the game as Madrid dominated possession, but couldn't find the cutting edge.
Cristiano Ronaldo had several shots, but City's packed defence restricted Madrid to only a handful of close-range opportunities.
Real continued to dominate possession early in the second half, but it was City who shocked the crowd on 69 minutes as Yaya Toure broke away to slot a pass to Eden Dzeko, who calmly slotted past Iker Casillas.
However the lead didn't last long, with Real left-back Marcelo cutting inside to curl a right-foot shot past Joe Hart on 76 minutes, with help from a deflection off Javi Garcia.
City stunned the Bernabeu again eight minutes later, Aleksandar Kolarov's free-kick curling into Casillas's bottom corner, before Karim Benzema guided a low left-foot shot beyond Joe Hart to make it 2-2 on 86 minutes.
The final word was left to Ronaldo, who has complained of feeling sad at Madrid in recent weeks but looked anything but depressed as he stormed inside to slam home the winner as the match entered injury time.
Meanwhile in France, Arsenal made light of the absence of Arsene Wenger, who was serving a UEFA suspension, as goals from Lukas Podolski and Gervinho clinched victory in Montpellier.
With Steve Bould directing from the dugout in Wenger's absence, Arsenal went behind early on when Montpellier's Younes Belhanda stroked home a penalty, but the visitors soon asserted their superiority.
The Gunners were in front by the 18th minute, and held on to their advantage with some resolute defending to ensure a perfect start to their Champions League campaign.