And then there was one. Following Real Madrid CF's loss to Sevilla FC on Sunday, TSG 1899 Hoffenheim now hold the honour of being the only club in Europe's top divisions yet to succumb to a league defeat this season.
The achievement is even more impressive when considering that TSG were bottom of the Bundesliga the start of 2016. As they prepare to put their record on the line again on Saturday, when they visit FC Augsburg, bundesliga.com asks the question – just how have they stayed unbeaten?
Watch: Highlights of Hoffenheim's Matchday 16 draw with SV Werder Bremen:
The Nagelsmann factor
Any analysis of Hoffenheim's upturn in fortunes has to start with their coach, Julian Nagelsmann. Since taking over from Huub Stevens in February, the 29-year-old has taken TSG from the relegation battle to the fight for Europe, picking up more points in the Bundesliga (51) than every team except FC Bayern München (74) and Borussia Dortmund (60).
A former disciple of Thomas Tuchel at Augsburg, Nagelsmann has been coaching since his early 20s, after a persistent knee injury ended his playing career. He may be young, but he is certainly not short of ideas, as Hoffenheim's numerous tactical innovations this season have shown.
"We have a plan for every match situation," explains defender Niklas Süle. "It's an incredibly flexible system. We can switch easily between three, four and five at the back during a game. We're more unpredictable to play against this season, which is one of our big strengths."
Nagelsmann has certainly kept his opponents guessing. Having abandoned a 4-3-3 system fairly early on in the campaign, he has experimented with any number of variations on a three- or five-man defence, which only 1. FC Köln have managed to get the better of – in the DFB Cup.
Watch: Ambitious Hoffenheim putting their faith in young talent:
By his own admission, though, Hoffenheim's transformation has as much to do with man-management as any tactical revolution. He once described coaching as "30 per cent tactics and 70 percent psychology" – and his ability to get the most out of players considered past their best has been a hallmark of his tenure.
Take Sandro Wagner. Touted as a potential star after winning the UEFA European Under-21 Championship with Germany in 2009 alongside future world champions such as Manuel Neuer, Jerome Boateng and Mats Hummels, the former Bayern man failed to build on his early promise, enjoying mixed fortunes with SV Werder Bremen and Hertha Berlin. His renaissance, which began at SV Darmstadt 98 last season, has continued under Nagelsmann – and he is currently Hoffenheim's leading scorer with nine goals in the Bundesliga.
Dortmund youth product Kerem Demirbay spent last season on loan at second-tier Fortuna Düsseldorf, before joining from Hoffenheim over the summer. The 23-year-old has proved another inspired signing, notching up three goals and four assists – including the stunning opener in the 1-1 draw with Bayern.
Nagelsmann has also given a number of home-grown players a chance to shine. Süle, 21, has belied his tender years with a series of assured performances at centre-back, contributing to Hoffenheim's defensive solidity (only 17 goals conceded in 16 outings). Having made his Germany debut in August, Süle also popped up with a winner against Hertha on Matchday 9.
There's no 'i' in team
Beyond their individual talents, Hoffenheim's unbeaten streak has been built on their collective strength and a newfound sense of determination. Nowhere was this better displayed than in the astonishing 4-4 draw with 1. FSV Mainz 05 on Matchday 2. Trailing 4-1 at half-time, Nagelsmann's charges battled back after Mainz were reduced to 10 men, and even came close to snatching the unlikeliest of victories in the dying minutes.
"From his first day in charge, Julian boosted our self-belief," Süle points out. "He'll speak to you honestly and directly about anything. He told us, 'It can't get much worse, guys. I want to see you playing good football.' It's great to have that level of trust, when you have your backs to the wall. It started paying off straight away."
Watch: Hoffenheim come from 4-1 down to snatch an incredible draw against Mainz:
Seventeen not out?
Augsburg will provide an interesting test for Hoffenheim as Nagelsmann returns to the club where he started out his coaching career. Die Fuggerstädter are currently on a run of just one defeat in their last seven, and have four points from their two games under new coach Manuel Baum. Nagelsmann got the better of his former club in his only previous encounter last season - a 2-1 win in Sinsheim - but he is yet to face his old flame on Augsburg soil. Could there be a more perfect place for the young strategist to make it an entire first half of a season without defeat?
Hoffenheim may be unbeaten, but they are still a point off Eintracht Frankfurt and the UEFA Champions League positions. And having drawn six of their last seven Bundesliga outings, the Sinsheim club will be keen to prove that winning does come as naturally to them as avoiding defeat. Victory over Augsburg would certainly send out a message at the start of 2017 - as well as boosting Hoffenheim's hopes of a maiden European campaign.