After going behind early on, Barca took charge and equalised through Perez just before the break.
Abel Ruiz, who played a key role in the equaliser, doubled Barca’s advantage early in the second half, nipping in to score after Busquets’ header crashed off the bar.
Soon after, Jordi Mboule broke through to flick the ball on to Lee to tap home the third.
Mboula saved the best until last as he collected the ball from the halfway line before slaloming his way through the Dortmund defence to complete the scoring.
