Complex sentence: This run of good form ended with a 2--1 defeat to Hannover 96, and losses to Borussia Dortmund and Mainz 05 soon followed, allowing Dortmund, the previous season's champions, to overtake Bayern at the top of the table.
Split into simpler sentences: This run of good form ended with a 2--1 defeat to Hannover 96, and losses to Borussia Dortmund and 1. FSV Mainz 05 soon followed, allowing Dortmund, the previous season's champions, to overtake Bayern at the top of the table.