An own goal from Iker Casillas helped Borussia Dortmund record a 1-0 away win over Porto in Thursday's Europa League last-32 tie to make it a 3-0 aggregate success for the Bundesliga side.
Hosts Porto knew they needed an early goal to boost their chances of a comeback after their first-leg loss, but were dealt a major blow halfway through the first half when Casillas gifted Dortmund the lead in unfortunate fashion.
The former Real Madrid goalkeeper did well to deny Marco Reus from close range, but Pierre-Emerick Aubameyang was first to the rebound - in what seemed to be an offside position - and unleashed a shot that crossed the line after hitting the crossbar and Casillas.
Evandro, Silvestre Varela, Vincent Aboubakar and Yacine Brahimi all had good chances to level the score - the latter hitting the crossbar late on - but Roman Burki proved to be too much of an obstacle between the sticks as it remained 1-0 as Dortmund booked their spot in the last 16.
Casillas reacted well to keep out Reus' volley after a cross from the right, only for Aubameyang to pounce on the rebound and see his shot go in via the woodwork and the unfortunate Porto goalkeeper.
Aubameyang thought he had doubled Dortmund's lead at the hour mark after being set up by Henrikh Mkhitaryan, only for referee Mark Clattenburg to blow for offside.
A fine Burki save denied Suk Hyun-jun with 15 minutes remaining before substitute Brahimi came incredibly close to equalising in the closing stages with a powerful strike against the crossbar.
Mkhitaryan also hit the woodwork in the 90th minute as it somehow remained 1-0 to Thomas Tuchel's men.
