Bayern Munich threw away a two-goal lead to fall to a 3-2 defeat away at Borussia-Park on Friday.
The hosts found themselves ahead as early as the 20th minute after referee Harm Osmers pointed to the spot for a stupendous handball in the area by Florian Neuhauss.
Osmers had initially waved play on but replays by VAR made him change his decision. Robert Lewandowski made no mistake from 12 yards to score his 20th Bundesliga goal of the season.
Bayern Munich soon doubled their lead when Leroy Sane and Leon Goretska combined beautifully, allowing the latter to score from outside the area with a thunderous effort.
At this point, it seemed like the defending champions would cruise their way to another victory. However, the hosts had other ideas, and Jonas Hoffman halved the deficit in the 36th minute.
Hoffman levelled matters right before half-time, with his goal standing following a brief VAR review for offside.
It took just four second-half minutes for Monchengladbach to take the lead. Florian Neuhaus made amends for giving away the spot-kick by converting an excellent pass from Hoffman with a curling finish that nestled in the top-right corner.
After going ahead, the hosts sat back to protect their lead. Despite facing some late pressure from the Bavarian giants, they ultimately held on for the win, with Matthias Ginter clearing off the line from Niklas Sule in the 91st minute.
The game did not turn out as expected for Bayern Munich. Here, we shall have a rundown of five talking points from the fixture.
#5 Manuel Neuer's wait for a Bundesliga clean sheet goes on
After a couple of sub-par seasons, Manuel Neuer got back to his brilliant best to inspire Bayern Munich to the treble. He was deservedly rewarded as the best goalkeeper in the world for his efforts.
However, this season has been far from a stellar one for the Germany international, with this defeat continuing a run of 10 games without a Bundesliga clean sheet for him.
Incredibly, the last time the 34-year-old kept a league clean sheet was in the 5-0 demolition of Eintracht Frankfurt on 24 October last year. Since then, he has conceded 13 goals in just 10 Bundesliga fixtures.
This is the longest stretch he has gone without a league clean sheet in his career but he has hardly been helped by the porous defence in front of him.
There were defensive errors involved in all three of Monchengladbach's goals. Benjamin Pavard were disposed in the build-up to the opening goal, while Kimmich and Sule were at fault for the other two goals.
If Bayern Munich are to successfully defend their league title, it is imperative that they sort themselves out at the back.
#4 Impressive Jonas Hoffman and Lars Stindl put Bayern Munich to the sword
Jonas Hoffman put out a man-of-the-match performance with two goals and the assist for the winner. However, his captain Lars Stindl was almost equally as integral to the victory.
It was Stindl who set Hoffman up for both of his goals with two pristine through-balls. He also showed great leadership, ensuring his teammates did not lose their confidence despite going two goals down.
He contested 11 duels, made one interception and completed two clearances before departing the field for Hannes Wolf in the 82nd minute as Marco Rose sought to shut up shop.
Hoffman was, however, the pick of the bunch on the field against Bayern Munich and showed great composure for his two finishes.
His awareness and sense of anticipation was also on display for the third goal, as he calmly dispossessed Sule before teeing Neuhaus up to score what proved to be the winner.
#3 Bundesliga title race blown open
Bayern Munich are nine-time defending champions of the Bundesliga and are overwhelming favorites to make it 10 in a row come May.
Having said that, the Bavarians came into this clash with just one point more than second-placed RB Leipzig and would have sought a victory to solidify their spot at the summit.
However, they failed to do so, handing the advantage back to Leipzig, who can go top if they get a victory in their game on Saturday.
Julen Nagelsmann's side will, however, have to be at an optimum if they are to get all three points. They will square off with 4th-placed Borussia Dortmund at the Signal Iduna Park in a clash that could have huge ramifications in the title race.
#2 Borussia Monchengladbach continue fine run of form
Borussia Monchengladbach were among the early pacesetters in the Bundesliga, but a disappointing sequence of results in December saw Die Borussen fall off the pace.
They kicked off the month with a 3-2 home defeat to Inter Milan in the Champions League and did not win any of their next five games in all competitions.
A 5-0 trashing against lowly Elversberg in the DFB Pokal saw Borussia Monchengladbach end the year with a win. They brought this form over into the new year with another 1-0 win away to Arminia Bielefeld.
The pick of the bunch is, however, this victory over Bayern Munich. The three points from the win help them climb up to 7th on the standings, just one point behind Dortmund in 4th.
#1 Impressive Robert Lewandowski continues brilliant scoring run for Bayern Munich
Last season was inarguably the best campaign of Robert Lewandowski's career, with his performances helping Bayern Munich to a second continental treble.
The 32-year-old's displays saw him have a clean sweep of almost all individual awards for the year, although he lost out on a maiden European Golden Shoe to Lazio's Ciro Immobile.
The fact that the Bundesliga has just 34 games in a season as opposed to 38 in other mainstream European leagues puts the Poland international at a disadvantage. However, he has continued from where he left off last season with another record-breaking campaign.
So far, Lewandowski has scored 20 goals for Bayern Munich in the Bundesliga, with eight of those coming consecutively in his last five games.
Despite ending up on the losing side, Lewandowski added yet another goal to his tally on Friday. At this rate, he is odds-on to break Gerd Muller's all-time record of 40 goals in a single Bundesliga season.