Two late goals in two minutes from Sergi Roberto and Luis Suarez gave Barcelona a remarkable 2-1 home win over Bayer Leverkusen in Champions League Group E.
Trailing 1-0 with 10 minutes to go, Sergi poked in a rebound from close range, and moments later Suarez swept the ball home from just inside the area.
Kyriakos Papadopoulos put the German side ahead after 22 minutes from a corner, with Barca keeper Marc-Andre Ter Stegen beaten in the air.
For reigning champions Barca, who were without their injured talisman Lionel Messi, it was a frustrating game of missed chances until their pressure told.
Barca have four points from two games in Group E and Leverkusen have three.
In the group's other game Belarus champions BATE Borisov shocked injury-hit AS Roma with an entertaining 3-2 home win.
BATE went 3-0 up in the first 30 minutes through Ihar Stasevich and two from Filip Mladenovic.
The Serie A club hit back after the break and reduced the deficit with strikes from Gervinho, after 66 minutes, and Vasilis Torisidis eight minutes from time.
Roma's Alessandro Florenzi also hit the crossbar late on but BATE held out to move on to three points in Group E. Roma are bottom of the section with one.
Bayern Munich and Poland striker Robert Lewandowski continued his remarkable scoring run with a hat-trick in a 5-0 thrashing of Dinamo Zagreb to snap the Croats' 45-game unbeaten run and take control of their Champions League group.
In an explosive first half in which Bayern were 4-0 up inside half an hour, Lewandowski, who has notched a staggering 10 goals in their last three matches, including five in a record nine-minute spell against VfL Wolfsburg last week, netted twice in seven minutes after Brazilian Diego Costa had put Bayern ahead.
Mario Goetze added his second of the campaign before Poland captain Lewandowski chipped keeper Eduardo in the 55th minute for his third goal as the title favourites moved to a maximum six points from two Group F matches.
Dinamo, unbeaten in 45 consecutive matches in all competitions before Tuesday and winners at Arsenal in their opening group game, were mere observers witnessing Bayern's awe-inspiring display of speed, skill and strength.
Arsenal's Champions League hopes were left dangling by a thread after they lost an astonishing clash 3-2 to Olympiakos Piraeus, who won a competitive European match in England for the first time in 50 years.
Jose Mourinho suffered a nightmare homecoming as Porto, the club he led to the Champions League title in 2004, inflicted a 2-1 defeat on his woefully out-of-sorts Chelsea side in Group G
Elsewhere in Chelsea's group, goals from Andriy Yarmolenko and Aluisio Junior Moraes gave Dynamo Kiev a 2-0 victory over Maccabi Tel-Aviv while in Group H, Valencia won 1-0 in Lyon and Zenit St Petersburg beat AA Gent 2-1.
