1. FC Union Berlin suffered a 0-1 defeat at Mainz with a penalty from Moussa Niakhate securing all three points for the relegation-threatened home side.

The 24-year-old converted from the spot after 22 minutes to put the hosts ahead and the goal would go without reply at the OPEL-Arena.

Mainz: Zentner; Da Costa, Bell, St. Juste, Niakhate, Mwene; Latza (Tauer 80), Kohr; Szalai (Glatzel 80), Onisiwo (Burkhardt 83), Barreiro

1. FC Union Berlin: Luthe; Trimmel, Schlotterbeck, Knoche, Friedrich, Gießelmann (Ryerson 60); Andrich, Gentner (Griesbeck 60); Teuchert (Musa 73), Ingvartsen (Endo 80), Awoniyi (Pohjanpalo 73)

Christopher Trimmel returned to the pack from suspension – the captain sat out the last 90 minutes in the Bundesliga at home to Borussia Mönchengladbach. After picking up a knock last week, Andreas Luthe took his place between the sticks and new signing Petar Musa was named in the matchday squad for the first time since joining from Slavia Prague on loan. Although Mainz occupied second last in the Bundesliga, the Carnival Club have improved under new coach Bo Svensson. Mainz picked up a victory at home to RB Leipzig and a point away to Borussia Dortmund, while looking more organised and competitive. Svensson's team put Union into uncomfortable situations early on without creating any clear chances. Union dealt with the numerous aerial duels and the battle to win the second balls in the centre of the pitch. After 20 minutes, referee Sascha Steegeman pointed to the penalty spot when Nico Schlotterbeck trampled on the foot of Karim Onisiwo. Mainz's Niakhate stepped up and established his position as the team's top scorer, firing past Luthe from 12 yards. Urs Fischer's team were given no time to settle on the ball and were immediately put under pressure. Steegeman gave out a couple of cautions for late challenges, including for Dominik Kohr and Leandro Barreiro Martins in Mainz's central midfield. The creative spark wasn't there for the visitors in forward positions – one of the few opportunities was on 33 minutes when Cedric Teuchert sent Taiwo Awoniyi through on goal but the assistant referee flagged for offside. The Nigerian striker sniffed an opportunity, however, about three minutes before the break as Mainz failed to clear their lines from a free-kick. The ball dropped to Awoniyi in a good position, but goalkeeper Robin Zentner charged out and blocked the angle to protect his clean sheet.

Union will have been readied for a stronger fight in the second half, but Fischer's side had to turn into defensive-mode within about 100 seconds of the whistle. Adam Szalai was free in the six-yard-box and the reactions from Andreas Luthe prevented Union from going two behind. On a bobbly pitch due to the adverse weather, Union's possession game struggled to take shape. It was a forceful diagonal from Nico Schlotterbeck which opened up the Mainz defence, the touch from Teuchert was strong but the striker's effort was saved by Zentner. Unfortunately, the stuffing was knocked out of the Köpenick club in the 55th minute when Schlotterbeck was awarded his second yellow card and sent down the tunnel. Union played on with 10 before Fischer tweaked his side from the bench – Julian Ryerson and Sebastian Griesbeck getting the nod in place of Niko Gießelmann and Christian Gentner. Zentner's highlight of the match was a fine save to parry a dangerous volley from Marcus Ingvartsen, the Dane using some quick thinking at the edge of the box. Union certainly needed some threat in the box and Fischer twisted with a debut for Musa and a sub appearance for Joel Pohjanpalo. The two combined in flashes with Pohjanpalo desperately unfortunate not to get more than a stud's contact on a loose ball with 10 minutes go. While Keita Endo was given the last 10 minutes to impress, Mainz's shored up defence stood the test. In fact, Andreas Luthe's actions prevented the game from being over as a contest before stoppage time. Mainz's new signing Robert Glatzel roamed clear of the Union defence in the final minutes but Luthe denied the former Cardiff City striker. At the other end, Pohjanpalo saw a shot blocked and Andrich fired wide as the Köpenick club ran out of ideas in Mainz.

1. FC Union Berlin will need to put a disappointing defeat to one side as the games come regularly in the Bundesliga. Urs Fischer's side host bottom-of-the-table Schalke next Saturday at 18:30 CET at the Stadion An der Alten Försterei.