The 33°C heat played a huge role from the off - under the sweltering sun, both sides were forced to conserve energy and pick their moments to attack the opposing goal. As such, the first half was a scrappy affair as the two teams effectively cancelled each other out.

The visitors’ Frederik Ronnow was the slightly busier goalkeeper, but he was not put under any real pressure. The stars of the opening 45 minutes were, in fact, the Union and Mainz supporters who, despite the high temperatures, provided a fantastic atmosphere.

The beginning of the second period could hardly have been in starker contrast to the first. As a couple of clouds appeared in the overhead sky, both sides provided far more attacking threat.

Niko Giesselmann and Julian Ryerson came close to beating Robin Zentner between the Mainz sticks, while Ronnow was forced into a couple of saves at the opposite end - Karim Onisiwo’s shot, in particular, stung the hands of the shot-stopper.

As time progressed, the end-to-end pace of the game dissipated. The introduction of summer signing Angelo Fulgini helped give Mainz control of the game, but clear-cut chances remained few and far between.

After being played in by the Frenchman, Marlon Mustapha produced some clever footwork down the left flank to create an opening, but could only stab a stretched shot wide of the post.

Back-to-back European qualifications have raised expectations of Union, and manager Urs Fischer will perhaps be disappointed his team could not provide more threat. Still, like Mainz, they remain unbeaten in all competitions this season, and can take plenty of positives from their strong defensive performance.

Flashscore Man of the Match: Genki Haraguchi (Union Berlin)