Hoffenheim's coach Markus Gisdol said he expected a replay.
"Anything else would be a joke," he said.
Kiessling's first reaction was to turn away in frustration at missing the chance and hold his head in his hands. Only when his teammates surrounded him in celebration did Kiessling also raise his arms in tepid triumph.
"I didn't really see it, I turned away but I was surprised to see the ball in. I didn't know how it got in," Kiessling said.
The incident resembled Thomas Helmer's famous "phantom goal" for Bayern Munich against Nuremberg in 1994 that finished in a 2-1 Bayern win. That match was replayed and Bayern won 5-0 to capture the title.
Brych said, "there was a corner and then the ball was in the net."
"I had a slight doubt but the reaction from the players was clear, nobody was against (the decision)," Brych said.
Brych said that none of the players including Kiessling had told him that it wasn't a goal.
It wasn't Brych's only controversial moment. He disallowed a Hoffenheim goal that was clearly onside and incorrectly awarded a penalty to Hoffenheim, although the spot kick was missed.
The victory put Leverkusen atop the standings, at least until Saturday's matches.
Sidney Sam scored against the run of play to put Leverkusen ahead after 26 minutes and Kiessling's "goal" doubled the lead in the 70th before Sven Shipplock pulled one back for Hoffenheim late in the match.
In the 82nd, Brych awarded a penalty for Hoffenheim although Roberto Hilbert played the ball and Roberto Firmino fell over him. The tackle was outside the box anyway.
Firmino himself took the shot but Leverkusen goalkeeper Bernd Leno stopped it. Firmino pounced on the rebound but hit the post and Emir Spahic's clearing attempt also hit the post before the ball was finally kicked away.
Sam found the space to slot into the low corner despite facing three Hoffenheim defenders in the 26th.
Gonzalo Castro did the work, delivering the ball after an unchallenged run down the middle and Sam scored his league-high seventh goal of the season.
Hoffenheim was the team dictating play but could not use its chances and also had the misfortune to have a regular goal mistakenly disallowed for a non-existent offside.
Kevin Volland's attempt was blocked at the last moment, Sejad Salihovic's free kick was cleared on the line and Anthony Modeste missed Hoffenheim's best chance when Leverkusen goalkeeper Bernd Leno managed to divert his point-blank shot into the corner.
While Hoffenheim wasted half a dozen chances, Leverkusen did look dangerous on the rare break.
Modeste had another header saved in the second half, while on the other side Castro's shot was palmed away by Koen Casteels.