League leader Union Berlin hosts fourth-placed Dortmund while 10-time defending champion Bayern welcomes second-placed Freiburg, a team that was unbeaten in 10 games across all competitions before its Europa League game at Nantes on Thursday.

Union is two points ahead of Freiburg, which itself is two points ahead of Bayern and Dortmund after nine rounds.

The surprise leaders' success is built on mean defenses, efficiency in front of goal, and continuity - both Union coach Urs Fischer and Freiburg counterpart Christian Streich are the longest serving coaches in the Bundesliga.

Fischer took over Union in July 2018 and led the club to promotion in his first season, while Streich has been Freiburg coach since 2011, overseeing its promotion as second-division champion in 2016 following its demotion the season before.

``You only have continuity in a club if a team achieves results that exceed expectations,'' Streich said this week. ``It's not like you can say, `Hey, the coach should stay for many years so that there's continuity in a club.'''

The 57-year-old Streich is back after missing his team's 2-2 draw at Hertha Berlin due to a coronavirus infection. ``I didn't have a lot of fun in front of the television,'' he said.

Neither Streich nor Fischer have any attention-grabbing stars, but they count on full commitment, hard work and a willingness to suffer when the players need to defend. No other teams have conceded fewer goals in the Bundesliga.

Union's 1-0 win in Stuttgart last weekend was not the first time this season that Fischer's team ground out a result through sheer doggedness and a little luck - Stuttgart twice hit the post. Paul Jaeckel's late corner from a header was enough for the team's sixth win.

``We had the necessary bit of luck. I think it's to do with where you are in the table,'' Fischer said. ``We needed it. But I believe also that we had to give a lot to get that luck.''

Union is unbeaten in 10 games at home, though it has lost each of its last three meetings against Dortmund since a win in December 2020.

Union held visiting Bayern to 1-1 in September. Dortmund will present a different challenge at Stadion An der Alten Forsterei on Sunday, when the visitors will aim to play more directly following coach Edin Terzic's and Mats Hummels' criticism of the players' tendency to overplay the ball.

``If you look at the program we've had in the last six days with three games, perhaps it's not surprising the freshness isn't there,'' Terzic said after Dortmund's 1-1 draw with Sevilla in the Champions League on Tuesday, days after the team's late 2-2 draw with Bayern. ``Still, we're not happy and it's no excuse. It's just one of the reasons. We simply have to play much more precisely and effectively.''

Dortmund has dropped points in four of its nine league games, while Bayern has four draws and one defeat.

The Bavarian side is happy to have qualified for the Champions League knockout stages from a tough group with the likes of Barcelona and Inter Milan, but the focus is clearly back on the Bundesliga - particularly after last weekend's disappointment in Dortmund.

``We ourselves are to blame for this draw, as we should have decided the game earlier or defended more consistently,'' Bayern CEO Oliver Kahn wrote on Twitter after Anthony Modeste's late leveler. ``But it continues and we want to get to first place as quickly as possible!''

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