Carlo Ancelotti's Bayern host Borussia Dortmund on Saturday evening when Robert Lewandowski and Pierre-Emerick Aubameyang -- the league's top scorers -- go head-to-head.
But before the heavyweight clash in Munich, second-placed Leipzig took their chance to reduce the 10-point gap and sealed the win in a dramatic final five minutes.
Hosts Leipzig were reduced to 10 men when captain Willi Orban was sent off for a second yellow card on 88 minutes for a marginal foul on Leverkusen's Germany forward Kevin Volland.
With a large hint of sarcasm, Leipzig's 24-year-old captain shook hands with the referee before going off having also been booked in the opening exchanges for a challenge on Volland.
But despite the numerical disadvantage, Leipzig claimed the three points through their Scandinavian combination.
Swedish playmaker Emil Forsberg put in the cross -- his 16th assistant of the season -- for Denmark's Poulsen to slot home for the dramatic winner.
Leipzig's victory was a big step towards direct Champions League qualification next season and they are seven points ahead of third-placed Hoffenheim, who crashed to a 2-1 defeat at Hamburg.
Elsewhere, ex-Germany midfielder Aaron Hunt stole the show for Hamburg -- who are unbeaten at home in their last nine league games -- with both goals as Hoffenheim suffered only their third defeat this season.
Wolfsburg, the 2009 German champions, remain on the brink  of the relegation battle in 14th -- just one point from the bottom three -- after their 4-1 hammering away to Schalke, who are in mid-table.
Schalke's Daniel Caligiuri scored against his former club while Germany's striker Mario Gomez scored his seventh goal in six games when he netted a late consolation penalty for Wolfsburg.
Also down the bottom of the table, Mainz are only out of the relegation places on goal difference after their 1-0 defeat at Freiburg when ex-Bayern striker Nils Petersen scored the second-half winner.
Borussia Moenchengladbach are challenging for a Europa League place next season after their 3-2 win at Cologne as captain Lars Stindl scored their winner nine minutes from time.
Hosts Cologne twice came from behind to equalise, but Gladbach held on to leave them just a point from the top six, which carries a European place for 2017/18.