Bayer Leverkusen moved within touching distance of a first Bundesliga title by beating 10-man Union Berlin.

Florian Wirtz's penalty gave Xabi Alonso's side a ninth successive win to stretch their lead over Bayern Munich to 16 points with six games remaining.

Bayern gave their title rivals a helping hand by letting a 2-0 lead slip to lose 3-2 at mid-table Heidenheim.

Leverkusen can end their long wait to be crowned German champions by winning at home to Werder Bremen next weekend.

Their coronation, however, is almost inevitable, with Alonso's unbeaten outfit needing just three points from the final 18 available to secure the championship.

Leverkusen will no doubt be keen to finish the job at the first time of asking in front of their own supporters.

They were frustrated in Berlin by several saves from Union keeper Frederik Ronnow, before the breakthrough came in first-half stoppage time after Robin Gosens saw a second yellow card for scything down Nathan Tella.

From the free-kick that followed, Christopher Trimmel handled Piero Hincapie's shot and, following a long video assistant referee check, Wirtz stroked home from the spot.

Leverkusen remain on course for a remarkable treble, having reached the German Cup final in midweek by thrashing Fortuna Dusseldorf 4-0 and they now prepare for the visit of West Ham in the Europa League quarter-final first leg on Thursday.