Leverkusen defeated Heidenheim 2-1 on Saturday with to goals from Jeremie Frimpong and Amine Adli.
Xabi Alonso's team now leads the Bundesliga by eight points, with Bayern Munich in second place.
With this victory, Leverkusen's unbeaten streak this season has reached 32 games, matching the mark set by Hansi Flick's Bayern during the 2019–20 and 2020–21 campaigns.
Leverkusen was frustrated by the tenacious hosts early on, but just before halftime, Frimpong's deflected shot entered the net, giving them the lead.
The master of midfield Florian Wirtz nearly sealed the victory with a brilliant pass that allowed Adli to get around the goalkeeper and score. With three minutes left, Tim Kleindienst of Heidenheim headed in a goal, marking the first league goal Leverkusen had let up in six hours of play.
Second-placed Bayern can narrow the gap when they play on Sunday at Bochum.