Berlin, Aug. 13 -- Borussia Dortmund has declared a challenge to end Bayern Munich's seven-year domination of the Bundesliga and is encouraged by signs of disharmony and unrest from the defending champion.

After pushing Bayern to the final day last season, Dortmund invested heavily over the summer to strengthen defensive frailties and give Swiss coach Lucien Favre more attacking options for his second season in charge.

Bayern's preparations have been overshadowed by the injury to Manchester City winger Leroy Sane, the club's No. 1 target to help fill the void left following the departures of Franck Ribery and Arjen Robben.

Coach Niko Kovac spoke of his certainty that the German international would arrive, leading to a very public put-d...