A last gasp winner caps the fightback as Leipzig keeps pace with Bayern Munich.
Lewandowski and Gnabry have netted twice as Bayern Munich went five points clear.
Leipzig has brushed past Hertha Berlin to close in on Bayern.
Leaders Bayern Munich have lost at Frankfurt in the Bundesliga.
Hoppe and Glory as Schalke avoid equalling the longest winless run of the Bundesliga.
Lewandowski has netted twice as Bayern roar back to floor Mainz.
Bosz is fuming as Leverkusen have missed a chance to top the Bundesliga.