Bayern warmed up for Wednesday's crunch Champions League last 16, return leg at home to Liverpool by hammering Wolfsburg 6-0 in Munich on Saturday with Robert Lewandowski leading the charge with two goals. The win allowed Bayern to claim top spot for the first time since September on goal difference from Borussia Dortmund, who struggled to a 3-1 home win over relegation-threatened Stuttgart.
On Sunday, thick snow on the pitch at Hanover counted against the hosts at 2-0 down when Japan forward Genki Haraguchi watched in despair when his shot dramatically slowed on its way towards an empty goal and was cleared.
"We're happy with the three points, but you can't analyse a match like that," said Leverkusen coach Peter Bosz. "The weather conditions meant it had nothing to do with football and wasn't much fun."
During the freak snowfall, Leverkusen took an early lead as Kevin Volland enjoyed a simple tap-in on 13 minutes after Hanover goalkeeper Michael Esser failed to hold a close-range shot. With ground staff cleaning the sidelines of snow as the game continued, Volland doubled the lead a quarter of an hour later, chipping Esser after Hanover yielded possession in their own half.
In worsening conditions, Hanover were denied on 33 minutes when Haraguchi rounded Leverkusen's keeper and fired at an empty net, but his celebrations proved premature. The Samurai Blue attacker watched as the orange ball stuttered and eventually stopped in the heavy slush, allowing Leverkusen defender Jonathan Tah to clear.
With the pitch markings no longer visible, the referee briefly halted the game to allow snow to be cleared. Second-from-bottom Hanover launched a second-half fight back as Jonathas leapt above the Leverkusen defence to nod home a Haraguchi cross on 61 minutes. Leverkusen then survived a penalty scare when the ball hit Tah in the area with 23 minutes left.
Hanover equalised when Leverkusen keeper Lukas Hradecky parried a free-kick, the ball went in off defender Mitchell Weiser for an own goal. Fifth-placed Leverkusen had the final word three minutes from time when Kai Havertz headed past Esser before Karim Bellarabi had a late effort ruled offside.