Forward Alcacer added the third goal deep in stoppage time.
Borussia Dortmund fought back to beat Cologne 3-1 with late goals from Achraf Hakimi and Paco Alcacer on Friday to make it two wins out of two in the Bundesliga this season.
Cologne’s Dominick Drexler had nodded in at the far post just before the half-hour to open the scoring with the hosts looking far more aggressive than Dortmund, who fell behind for the second consecutive league game.
A Marco Reus free kick was Dortmund’s best chance in the first half and they had to wait until the 70th minute for Jadon Sancho’s equaliser, his second goal in two league games.
Hakimi then rose above two defenders to head in a Lukasz Piszczek cross at the far post to put them ahead and forward Alcacer added the third goal deep in stoppage time.
Champions Bayern Munich, who stumbled to a 2-2 draw in their opener last week, travel to Schalke 04 on Saturday.