Bundesliga leaders Borussia Dortmund scored five second-half goals in a crushing 6-1 win at Cologne that maintained their five-point lead at the top of the table on Sunday. There was little sign of what was to come when Milivoje Novakovic headed Cologne ahead after 11 minutes. But Lukasz Piszczek equalised with another header in the 26th minute and quickfire goals from Shinji Kagawa and Robert Lewandowski after the break put Dortmund in control. Ilkay Gundogan, Kagawa and Ivan Perisic added three more in the last 15 minutes as Cologne capitulated in shambolic fashion. Champions Dortmund, unbeaten in their last 21 league games, have 62 points from 27 games and Bayern Munich, who beat Hanover 96 2-1 on Saturday, have 57. (For more sports news and updates, follow Ahram Online sports on Twitter: @AO Sports)