Five-star Dortmund hammer Hamburg
Kevin Grosskreutz gave Dortmund the lead after 16 minutes, before Lewandowski made it 2-0 in the 37th minute. Blaszczykowski got a third goal in the 58th minute and the Polish international added a second from the spot after 76 minutes.
Dortmund, undefeated in their last 12 games, improved to 37 points but trail Bayern by four goals, while Hamburg's first defeat under Thorsten Fink, after two wins and six draws, leaves them on 19 points.
Grosskreutz gets the first
The visitors dominated from the start, with Lewandowski and Neven Subotic both striking just over the framework in the first four minutes.
The guests pulled ahead after 16 minutes as Grosskreutz gained control of the ball and passed on to Shinji Kawaga and the Japanese international fed Grosskreutz, who beat Hamburg goalkeeper Jaroslav Drobny from 11 yards.
Hamburg nearly equalised a minute later but Guerrero shot wide from six yards out. Drobny kept his team in the game with a superb save from Subotic's header in the 28th minute.
Lewandowski had a goal disallowed in the 31st minute but the Polish international made it 2-0 six minutes later, collecting a ball from Blaszczykowski, advancing and beating both Dennis Aogo and Drobny.
Dortmund wrapped up the points when Blaszczykowski made it 3-0, scoring from the edge of the box after a pass from Lewandowski.
Blaszczykowski scored his second goal of the day from the penalty spot in the 76th minute after Dennis Diekmeier took down Moritz Leitner in the box.
Lewandowski made it 5-0 with seven minutes remaining after some fine Dortmund passing, before Guerrero broke the visitors' shut-out when he collected a loose ball in front of goal and converted.