Each team had a man sent off as Bayer Leverksuen were held to a goalless draw by Freiburg on Saturday.
For much of the first half, it looked like the supporters would have to sit through an uneventful 45 minutes, but Emir Spahic ensured there would be drama as he picked up a second yellow card just before the half-hour mark to throw Leverkusen into trouble.
Freiburg grew in confidence after the dismissal, and created the first chance of the game before the break when Felix Klaus sent a powerful strike past the post.
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Despite seeing the odds stacked against them, Bayern were inches away from breaking the deadlock in the second half when Hakan Calhanoglu fired a long-range effort just over the crossbar.
It was a level playing field once again in the 78th minute when Pavel Krmas received his marching orders for a second bookable offence, but any chance of a late winner was gone when Son struck the crossbar with free kick.