Last season's runner-up broke the deadlock inside four minutes, when Alexia Putellas curled a stunning effort into the top-left corner.

Ewa Pajor knocked in the second, before Putellas turned provider, teeing up Esmee Brugts, who put the Blaugrana 3-0 up within 27 minutes to round off a stunning team effort.

While Bayern responded through Klara Buhl five minutes later, the hosts could smell blood, and Salma Paralluelo prodded home just before the break.

Barcelona's ruthlessness continued into the second half, with Pajor claiming her brace in the 56th minute, before substitute Claudia Pina registered a double of her own in the space of just four minutes.

Elsewhere, Juventus downed Benfica 2-1.

The Bianconeri had to come from a goal behind, after conceding a sixth-minute opener from Lucia Alves.

A header in each half from defender Cecilia Salvai ensured Juve clinched all three points and an opening win.

Meanwhile, Paris FC and OH Leuven played out an enthralling 2-2 draw, in what was a tale of two halves.

The hosts were two goals up inside 23 minutes, as Daphne Corboz and Clara Mateo both got on the scoresheet.

Yet, Leuven's second-half reply ensured it returned home with a share of the spoils, as Kim Everaerts and Sara Pusztai restored parity.