Sebastien Haller and Marco Reus scored a brace each for Borussia Dortmund to the top of the Bundesliga table on Saturday with a stunning 6-1 victory over Cologne.
Dortmund started the game with high intensity, and it paid off as they scored four goals in the first half. Guerreiro, Haller, Reus, and Malen all got on the scoresheet before Davie Selke scored Cologne's first goal in five matches.
Haller, who has been criticized for his lack of goals, scored his first double for Dortmund after 69 minutes, while Reus added another goal just a minute later to seal the thumping win.
The victory was a significant return to form for Dortmund, who suffered Champions League elimination at Chelsea and stumbled to a draw with derby rivals Schalke after starting the year with 10 straight wins.
The win sends Dortmund one point clear at the top of the Bundesliga table ahead of Bayern Munich, who will play Bayer Leverkusen on Sunday.
Dortmund will face Bayern after the international break on April 1.
On the other hand, Cologne is now winless in five and sits 13th, just six points clear of the relegation play-off spot.
The result leaves them in a precarious position and in need of points to stay out of trouble.