Union Berlin fans were singing - most likely tongue-in-check - about becoming German champions following their win over Borussia Dortmund on Matchday 10. Another 11 weeks later and they're level with leaders Bayern Munich ahead of their Matchday 22 showdown at the Allianz Arena, so what's to stop their dream becoming reality?

bundesliga.com presents five reasons why Union can win the Bundesliga title for the first time…

1) A fortress at the Alten Försterei

Back in 2019/20, Dortmund were the first Bundesliga team to find out how hard it can be to face Union in the capital. BVB's 3-1 defeat on Matchday 3 of the 2019/20 season - the Berlin club's first win in the Bundesliga - was a major shock. Now, though, results like Union's 2-0 win over Dortmund on Matchday 10 of the current campaign have become commonplace. "Iron Union" lost once at the Stadion an der Alten Försterei in 2020/21 and - on their way to finishing fifth - just twice in 2021/22.

This year they are unbeaten so far in their famous 22,000-capacity ground by the forest in the southeastern suburb of Köpenick. Including RB Leipzig and Dortmund, a total of seven teams have all left empty handed, while even defending champions Bayern Munich fell behind before earning a 1-1 draw. Alongside Leipzig and Freiburg, Union (P10, W7, D3, L0; 24 points) have the equal best home record in the Bundesliga this season, having played once fewer than their aforementioned rivals. In fact, they have only lost two of their last 43 Bundesliga games in Berlin.

Watch: See how Union beat Dortmund on Matchday 10 

With Bayern and Dortmund the only teams to win there in recent years, it's clear that opposing teams must dread a trip to one of the most atmospheric grounds in Europe. Some Union fans donated blood in a fundraising drive in tougher times and thousands volunteered to help with the redevelopment of the stadium in 2009. Many visit the stadium each year to sing Christmas carols. With that kind of connection between the supporters and the club, is it any wonder it's become such a treacherous trip for visiting teams? And with such passionate backing, could their strong home record lead them to what would be a quite remarkable first top-flight title?

2) A steely defence

The "Iron Union" nickname is a nod to the club's working-class roots, while the rhythmic, back-and-forth chant of “Iron! Union!” that their fans engage in must seem like a call to the players to keep up their workrate. Under Swiss coach Urs Fischer - who led Union to promotion via a play-off win over VfB Stuttgart in May 2019 - they have rarely been found wanting in that regard.

The passionate backing Union Berlin get from their loyal supporters is a big reason for their success. - IMAGO/Tilo Wiedensohler/IMAGO/camera4+

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"They throw themselves into every challenge and are very, very aggressive," Dortmund coach Edin Terzic said after his side's defeat in Berlin earlier this season. "They help each other, support each other, never leave a teammate alone… you're generally hit by two or three challenges within a few seconds."

The statistics also back up what's plain to see for anyone who watches Union in action, with the players covering a season-high 124.8 kilometres against Dortmund. They also rank second across the division for most aerial duels won (570) and top for distance covered (2,491 kilometres) - proving they are not only committed as a group but they're up for the fight week in, week out.

After the Dortmund encounter, Fischer suggested he was in awe of what his players had achieved, but also pointed out that it was a case of hard graft paying off.

"With this kind of physical commitment, you give yourself a chance of beating any team," the Union boss said.

Union's dependable centre-back Robin Knoche (l.) and midfield lynchpin Rani Khedira (r.) have had plenty of cause for celebration this season. - IMAGO/O.Behrendt/IMAGO/Contrast

Only Mark Flekken (nine) Koen Casteels (eight) and Gregor Kobel (seven) have kept more Bundesliga clean sheets than goalkeeper Frederik Ronnow (six) this term, while Union (24 goals conceded) have the second-best Bundesliga defence behind 10-in-a-row champions Bayern (21).

3) Ice-cold in attack

It's not just in defence that Union are ruthless. They have fired just four Bundesliga blanks all season and have been devastating since the turn of the year. In their six games of 2023 thus far, Union have scored 11 times and found the back of the net at least twice in five of them.

Sheraldo Becker is the club's top scorer with seven Bundesliga goals, but their real strength is being able to share the workload all over the pitch. Midfielder Janik Haberer has five - all coming in victories - while Jordan, Kevin Behrens and even centre-back Danilho Doekhi each have four league strikes.

In total, Union have had 12 different scorers so far this term and although they'd like to see Jordan get back to his early season best - the USA international scored three times and laid on two assists across his first six appearances - there will be fewer concerns in the ranks as long as everyone continues to chip in.

Watch: Deadly Duo Jordan and Becker

4) The best in Europe

Heading into the World Cup-enforced winter break, Union looked as if they were about to fall out of the title picture. They had led the Bundesliga from Matchdays 6-12 until a 5-0 demolition at the hands of Bayer Leverkusen on week 13 appeared to rock the Union ship.

Union had also lost to then bottom Bochum two weeks prior and, following the Leverkusen loss, they ended 2022 with a draw at home to Augsburg and defeat to Freiburg - eventually slipping to fifth and seven points back from Bayern at the turn of the year.

But they've been almost perfect in 2023 thus far, chalking up five wins and a draw to move level with the defending champions. Across Europe's top-five leagues, just Barcelona (six wins) and Dortmund (five) have also notched up a 100 percent record in 2023.

Watch: This is Union Berlin!

5) Never-say-die spirit

As the league position suggests, Union have consistently defied the odds this term and it's fair to say that Fischer's don't know when they're beaten. As evidenced in their 2-1 win at Leipzig, where they trailed their fellow title-chasers until Haberer's outstaning equaliser on the hour mark. Robin Knoche's penalty then went on to clinch all three points - vital ones as we head into the home stretch of what looks to be a history-making season.

And Union coming from behind to secure victory is not a new thing. They have claimed wins on four separate occasions having previously trailed this term, turning around 1-0 deficits against Borussia Mönchengladbach, Hoffenheim, Werder Bremen and Leipzig.

Watch: Union come from behind - again - to beat Leipzig

These 12 rescued points are more than any team in Europe's top five leagues have managed and it underpins everything that Union stands for under Fischer. And their coach - who signed a new contract in September - must be credited for being central to their success.

He has created a family atmosphere at the club, and in his typical low-key fashion he has regularly tried to shield his players from any hype. After the Dortmund game he said they shouldn't be dreaming about a Bundesliga title because they need to retain their focus. As for the fans? "They can dream," he said.

About the clubs

1. FC Union Berlin

An der Alten Försterei