Although the holders took the lead when Luis Suarez headed home an Ivan Rakitic cross from close range early on, the moment of the night - and surely of the season so far - was yet to come.
With 31 minutes on the clock at Rome's Stadio Olimpico, home defender Allesandro Florenzi won the ball back inside his own half and embarked on a run down the right.
The 24-year-old, almost 60 yards from goal just inside the visitors' half, looked up and saw Barcelona goalkeeper Marc-Andre ter Stegen off his line.
