The game marked exactly 500 days since Xabi Alonso took over as Leverkusen's coach, and the former Liverpool, Real Madrid and Bayern Munich player has proven himself to be a more than capable coach at the highest level.

Alonso has seen his team earn 103 points from the 48 Bundesliga matches he has coached it through. Only Pep Guardiola, Hansi Flick - whose Bayern side also went 32 competitive fixtures unbeaten in 2019 and 2020 - and Carlo Ancelotti have a better points-per-game ratio in the Bundesliga.

Such exhalted company did nothing to faze Alonso during last week's huge 3-0 win over title rival Bayern Munich, and his charges looked similarly confident away from home in this fixture.

Florian Wirtz tested Heinz Muller's reflexes inside four minutes, and Patrik Schick also tested the home goalkeeper, but clear-cut chances were largely at a premium early on.

Indeed it appeared the first half would end goalless, but Jeremie Frimpong ensured it wouldn't when he slammed home a shot with the aid of a deflection in stoppage-time at the end of the first period.

Frimpong fired off another warning shot early in the second half as he searched for his eighth goal of the season, before Heidenheim substitute Nikola Dovedan made Lukas Hradecky work for the first time with a deflected effort from inside the box.

Frimpong agains firednarrowly wide after a trademark run, but a spirited Heidenheim returned fire through Benedikt Gimber, whose 18-yard drive had Hradecky at full stretch to make the stop.

Wirtz then struck the crossbar as Leverkusen looked to double the lead, and it eventually did so when Wirtz found Amine Adli in the box, and he rounded Muller to slot home.

Kleindienst reduced the arrears with a close-range header, but Leverkusen held on for the win and moved eight points clear of Bayern, which will be confident of clawing it back to five points at Bochum on Monday (AEDT).