Jan Rosenthal scored twice, but later became one of five players sent off in Saturday's six games, as Freiburg came from behind to extend Schalke's winless run to six league games.
The only consolation for their fiery coach, Huub Stevens, was sports director Horst Heldt's promise on Thursday that the Dutchman's job is safe for the time being.
Kiessling's brace made the unsung striker the Bundesliga top scorer with 12 goals. Andre Schurrle was also on target as second-placed Leverkusen cut Bayern Munich's lead at the top to nine points at the Bundesliga's halfway mark.
Fuerth's Mergim Mavraj was dismissed for a second bookable offence, and his sending off was followed by that of Augsburg substitute Giovanni Sio, who got a straight red after only four minutes on the field.
Kiessling has been among the Bundesliga's leading scorers over the past few seasons but has won only six caps for Germany, finding himself overshadowed by Miroslav Klose and Mario Gomez.
Leverkusen reached the halfway mark with 33 points, compared to Bayern's 42, with Frankfurt a further three points behind.
Leverkusen's progress has gone almost unnoticed with Bayern hogging the limelight, and Schurrle said they did not expect to mount a challenge, despite the Bavarians' recent tendency to cave in at crucial moments of a campaign.
"Bayern are simply too good this year, we have to accept that," Schurrle told reporters.
"But we want to cut their lead as much as possible and, naturally, we won't want to give up on second place."
Adler was angrier at Leverkusen's final goal, in the 66th minute. L
