Cologne will have the chance to escape relegation in the final Bundesliga matchday next weekend after scoring a goal in stoppage-time to secure a 3-2 comeback win against Union Berlin on Saturday. Mainz, meanwhile, cruised to a 3-0 victory against Champions League finalists Borussia Dortmund, who rested several starters. With 32 points, Mainz are no longer in danger of automatic relegation and will remain in the Bundesliga if they defeat VfL Wolfsburg next weekend. Other results could lead to a relegation play-off against the third-placed in the second division. Union sit two points behind, cu…