Dortmund 5-1 Cologne: Haaland double in home debut sends BVB to Bundesliga top 3
Raphael Guerreiro put the hosts ahead from Jadon Sancho's cut-back after just one minute before Marco Reus doubled the lead after half an hour.
Sancho and Haaland's brace put the game beyond doubt in the second half, with Mark Uth scoring a consolation for the visitors, leaving Dortmund third in the Bundelsiga table and four points from the summit.