#1 Holstein Kiel
Kiel is another former top-flight side and they even won the German championship in 1912, but they haven't been in the top division since the Bundesliga was formed in 1963. Of all the surprising teams, their story is the most remarkable one as they are currently leading the 2. Bundesliga as a newly promoted team.
With 15 games played, Kiel has lost just twice in the generally very competitive league. The 117-year-old club owns the best attacking record in the division with 34 goals scored and they are also close to the best defensive record with 18 goals conceded.
Led by manager Markus Anfang, Kiel have managed to stay on top even through a rough patch, which currently has seen them win only one of the last four games.
The recent form is certainly a worry, but Kiel still had a 5-point gap ahead of the 3rd position, which would send the team to a promotion/relegation playoff with the 16th side of the Bundesliga.
Kiel could end up fading away as the season progresses, but it's fun to watch their current run. They are like the more nicer version of RB Leipzig without all the money, speeding through divisions all the way to the top. Only four seasons ago, Kiel were still in the 4th tier. I bet even the most optimistic fans couldn't imagine that the club would be fighting for a Bundesliga spot in 2018.