Ewa Pajor and Claudia Pina each scored twice as Barcelona's bid to reclaim the Women’s Champions League began with a 7-1 thrashing of Bayern Munich.
Barca, who were beaten by Arsenal in last season’s final after lifting the trophy in the two previous campaigns, edged ahead in the fourth minute thanks to a delightful curling finish from captain Alexia Putellas.
Poland international Pajor quickly doubled the advantage with an acrobatic close-range effort.
Esmee Brugts lashed home the hosts’ third in the 27th minute and then assisted Salma Paralluelo to make it 4-1 in first-half added time after Bayern forward Klara Buhl pulled a goal back.
Prolific striker Pajor clinically slotted past visiting goalkeeper Ena Mahmutovic 11 minutes into the second period to claim her second of the evening.
Substitute Pina, who was top scorer in last season’s Champions League with 10 goals, added to Bayern’s misery in the 88th minute before doubling her tally in added time to complete the scoring.
Two individual errors saw Arsenal's title defence get off to a losing start in a 2-1 defeat at home to Lyon.
Melchie Dumornay punished both mistakes to turn the game around after Alessia Russo’s early strike had put the Gunners ahead at Meadow Park.
Arsenal goalkeeper Daphne van Domselaar rushed her attempted pass out from the back and picked out Dumornay just outside her penalty area and the Champions League young player of the year for the last two seasons rolled the ball home at the second attempt.
Van Domselaar also had a hand in the visitors’ second in the 23rd minute, although Mariona Caldentey had to shoulder most of the blame.
The goalkeeper rolled the ball out to the Spain midfielder who turned straight into trouble and lost possession and when Katie Reid’s weak header dropped to Dumornay on the edge of the area she fired home.
That undid the ideal start given to them by Russo in only the seventh minute of this repeat of last season’s semi-final.
Ireland international Katie McCabe saw limited game time in Borehamwood, coming on with three minutes to go to replace Taylor Hinds.
Cecilia Salvai’s double earned Italian champions Juventus a 2-1 comeback win over Benfica in Turin.
Lucia Alves fired the Portuguese visitors into a sixth-minute lead, bursting into the box to rifle Nycole Raysla’s cutback into the roof of the net and score the first goal of the new league phase.
Juve defender Salvai headed Barbara Bonansea’s cross into the bottom-left corner in the 22nd minute to level before completing the turnaround four minutes from time by diverting home from a corner.
Belgian side OH Leuven battled back from two goals down to draw 2-2 at Paris FC.
Daphne Corboz and Clara Mateo put the French side in control at the break but second-half goals from Kim Everaerts and Sara Pusztai salvaged a point for the visitors.
