Bayern Munich returned to the top of the Bundesliga, Werder Bremen made history with another comeback, and Stuttgart suffered a frustrating defeat in Hamburg. Here are five things we learned from Matchday 6.

A week after putting six past Eintracht Frankfurt, RB Leipzig found themselves on the receiving end of the same punishment at the Allianz Arena, as Bayern Munich returned to the Bundesliga summit in emphatic fashion.

Borussia Dortmund, meanwhile, missed a chance to return to the top after a frustrating afternoon in front of goal against Union Berlin.

Elsewhere, Stuttgart were left to rue their missed chances in Hamburg, Freiburg suffered their first defeat of the campaign, and Werder Bremen made Bundesliga history in their draw with Paderborn.

Looking back at the weekend, here are five things we learned from Bundesliga Matchday 6.

Stuttgart's problems go beyond missed chances

Stuttgart will be wondering quite how they managed to leave Hamburg empty-handed on Saturday.

Sebastian Hoeneß's side had 24 attempts on goal, enjoyed 66% possession and created more than enough opportunities to put the game to bed before Miro Muheim's spectacular late winner.

Deniz Undav struck the post and Ermedin Demirović was guilty of wasting several promising openings, while Hamburg goalkeeper Daniel Heuer Fernandes was kept busy throughout the afternoon.

There was plenty to like about Stuttgart in the first two thirds of the pitch, particularly during the first half, but this was another league match where their good work counted for nothing.

The visitors then lost their way after the break, allowing Hamburg to take control for a spell in which Yussuf Poulsen twice struck the woodwork. VfB eventually regained the initiative, but still could not find a breakthrough.

Afterwards, Hoeneß felt his side had done enough to win, and it is difficult to disagree. However, Saturday's defeat was Stuttgart's fourth in six Bundesliga matches, leaving them with just six points.

Parts of their performances have been encouraging, with victories over Paderborn and Slovan Bratislava earlier in the week showing what they can do when things click.

The crucial concern, though, is that, as mentioned, only ‘parts’ have been encouraging, 

Stuttgart are creating chances and not scoring, while they have shown defensive vulnerabilities unseen in Hoeneß's prior years, even in the 4-1 win vs Köln, when the common theme of an awful start to the second half was present once again. 

Grischa Prömel has struggled in midfield since his summer arrival, the armband seems heavy on Undav, and the biggest signing, Dzenan Pejcinovic, has been unable to get going.

Things don't get much easier, with Atletico Madrid coming this week before facing bottom-dwellers Gladbach, but Hoeneß needs to see a response before things get urgent for a club reliant on European football to keep their squad together.

Bayern's attacking numbers are becoming ridiculous

Bayern Munich had 29 attempts on goal against Augsburg before the international break and scored twice.

On Saturday, they managed exactly the same number against RB Leipzig, but this time six found the back of the net.

It was a strong response from Vincent Kompany's side after consecutive draws against Augsburg and Viking FK, with Leipzig arriving in Munich after scoring six against Eintracht Frankfurt a week earlier.

Luis Diaz was the standout performer, scoring a hat-trick and providing an assist, but Bayern were excellent throughout the side.

Harry Kane's contribution was particularly impressive. The England captain repeatedly dropped deep to join Bayern's build-up play, creating space for Diaz and Michael Olise to exploit, which they did so often throughout the 90.

Bayern's second goal was a perfect example, with Kane collecting possession deep in his own half before finding Diaz, who set up Aleksandar Pavlovic to finish.

Leipzig could barely get near Kompany's midfield, while Bayern's pressing ensured the visitors struggled to get out of their own half for much of the opening 45 minutes.

Martín Demichelis's side failed to register a shot before the interval, by which point Bayern were already three goals ahead.

What has been particularly impressive about Kompany's Bayern since his arrival, is the ability to sustain that pressure, with Der Rekordmeister simply refusing to slow down even at 5-0.

Bayern have now scored 18 goals in their opening three Bundesliga home fixtures, a new league record, and 22 in six matches overall.

They haven't been perfect this season, with defensive lapses proving costly against Augsburg and Viking, but Saturday showed how punishing they can be when it all comes together in the final third.

Arsenal visit the Allianz Arena on Wednesday, and the Premier League leaders will certainly provide another test of Bayern's credentials.

Freiburg have little reason to be disheartened

Freiburg's unbeaten start came to an end at the BayArena on Sunday, although Julian Schuster will have taken plenty of encouragement from his side's performance.

The Breisgau outfit arrived as league leaders following five excellent results, but facing a Leverkusen side beginning to find form under Carles Martínez was always going to be a different challenge.

Freiburg took an early lead through Derry Scherhant and, even after Ibrahim Maza's equaliser five minutes later, prevented the hosts from establishing much rhythm.

Schuster's men looked comfortable in possession and regularly played their way through Leverkusen's attempts to press, with the hosts struggling to create clear openings for much of the second half.

In the end, a moment of quality from Maza made the difference after the 20-year-old worked his way through several Freiburg defenders to find Patrik Schick, who finished from close range.

There will be frustration at how Freiburg conceded both goals, particularly having looked so organised for much of the contest, but there is no reason to come away from Sunday with much concern, with Freiburg finding so many ways to compete in the early days of this term.

Sunday was arguably the toughest test of their season so far, and they came close to taking something from it.

With 13 points from six matches, Die Breisgauer remain just one behind Bayern and Dortmund, and the visit of the champions next weekend presents another opportunity to test themselves.

A title challenge is perhaps asking too much, but if Freiburg can continue playing at their current level, another season competing for European football, maybe even the Champions League looks well within reach.

Daniel Thioune will want more despite historic Bremen comeback

Three consecutive Bundesliga matches, three two-goal deficits, and seven points recovered from losing positions.

Werder Bremen have certainly provided plenty of entertainment in recent weeks, becoming the first side in Bundesliga history to avoid defeat after trailing by two goals in three successive matches.

However, unlike the dramatic victory over Augsburg and last weekend's draw in Dortmund, Saturday's comeback against Paderborn was met with a rather different reaction.

Niclas Füllkrug scored twice in five second-half minutes to rescue a 2-2 draw, adding more fuel to the debate of whether he stays at the Weserstadion.

But, Bremen had created enough opportunities to win comfortably, only to find themselves 2-0 behind after half an hour.

Marco Grüll and Chuki both passed up good chances before Stefano Marino opened the scoring for Paderborn, with some poor defending then allowing Steffen Tigges to double the visitors' advantage.

Füllkrug eventually brought Bremen level, taking his Bundesliga tally to six goals this season, but Daniel Thioune's side were unable to find a winner despite continuing to push forward.

There is an obvious positive in Bremen's refusal to accept defeat, and the return of Füllkrug has made a considerable difference to their attacking threat.

Yet, having conceded 12 goals across their opening six Bundesliga matches, there are still concerns about their defensive performances.

Thioune has been able to name an unchanged starting XI for five consecutive league fixtures, providing some much-needed consistency, but Die Grün-Weißen are continuing to make things harder than they need to be.

Saturday was a game they should have won, and the disappointment among the players, despite making history, perhaps shows how expectations have changed at the Weserstadion after last season's battle at the bottom.

Union are finally finding some defensive stability

Union Berlin conceded 17 goals in their opening four Bundesliga matches, including a humiliating 7-0 defeat to Bayern Munich before the international break.

For a side that has traditionally built much of its success around defensive organisation and making life uncomfortable for opponents, it was a particularly worrying start.

However, Saturday's goalless draw with Borussia Dortmund provided further evidence that Mauro Lustrinelli is beginning to address those problems.

Union had secured their first victory of the season against Elversberg a week earlier, keeping a clean sheet for the first time in the process before the obviously tougher test of Dortmund. 

However, Lustrinelli's side excelled on the day, limiting Niko Kovac's side to just 10 shots.

Janik Haberer was particularly impressive in an unfamiliar right-back role, while Rani Khedira also provided important protection in midfield, and Zeno van den Bosch and Felix Uduokhai looked far more assured in the centre of defence than Union's backline had during the opening weeks.

Dortmund enjoyed the majority of possession and improved after half-time, but Serhou Guirassy was largely isolated, and the visitors managed just two attempts on target.

BVB's attacking struggles deserve scrutiny, particularly following their Champions League defeat against Bodø/Glimt, but that should not take away from Union's performance.

Lustrinelli's decision to stick with the same starting XI that defeated Elversberg appears to be paying off, with his side now recording consecutive Bundesliga clean sheets for the first time in more than a year.

There is still work to be done, particularly going forward, but Union have at least started to resemble the difficult opponent that Bundesliga sides have become accustomed to facing at the Alte Försterei.