Can leaders Dortmund halt Bayern's Bundesliga domination?

"That's what we are all assuming in Munich," said Bayern coach Niko Kovac on Saturday, as the Bundesliga breaks for winter until January 18.

Their 3-0 victory at Eintracht Frankfurt this weekend was Bayern's fifth consecutive league win, moving them up to second, but Dortmund are eyeing a first Bundesliga title for seven years.

Here are five things we have learned from the first half of the Bundesliga season:

Crisis averted

Kovac, 47, has been in office for six months but has already survived a crisis after Bayern dropped to sixth in October after consecutive defeats by Hertha Berlin and Borussia Moenchengladbach.

The losses fuelled reports stars Thomas Mueller, Arjen Robben, Mats Hummels and Franck Ribery were unhappy with Kovac.

After a 3-2 reverse at Dortmund in November, Bayern were held to an embarrassing 3-3 draw at home to strugglers Fortuna Duesseldorf and Kovac was threatened with unemployment until a 5-1 drubbing of Benfica in the Champions League lifted the pressure.

"One must not forget we lost six points to three teams in the lower tier," said chairman Karl-Heinz Rummenigge referring to Bayern's disappointing draws with Freiburg, Augsburg and Duesseldorf over the last few months.

"There were discussions with Niko and some players -- now Niko and his team are at one again."

Dortmund's 'half cake'

For the first time since 2012, Bayern are not top going into the winter break and Dortmund have the potential to end the Bavarians' stranglehold on the Bundesliga trophy.

"But we have only eaten half the cake," insisted Dortmund captain Marco Reus, scorer of 11 goals this season with seven assists.

Alongside the injury-prone Reus, Paco Alcacer has been outstanding with 12 goals in as many league games.

The 25-year-old was initially signed on loan from Barcelona, but after scoring in each of his first five games, Dortmund signed him permanently and he scored the winner against Bayern in November.

However, it will be a huge test for Dortmund to deny Bayern for five more months with pundit Matthias Sammer warning that Lucien Favre's team are still "in the development phase".

English exports

English teenager Jadon Sancho has so far been the best youngster in Germany's top flight.

The 18-year-old has been involved in all of Dortmund's last nine goals in open play, scoring twice and providing three assists, while delivering the penultimate pass leading to the goal on another four occasions.

The ex-Manchester City winger is not the only English export dazzling in Germany.

Nineteen-year-old Reiss Nelson has scored six goals for Hoffenheim on loan from Arsenal, seizing his chance after finding opportunities limited in the Premier League.

Surprise package Gladbach

Borussia Moenchengladbach go into the winter break third -- which surprises even head coach Dieter Hecking.

"To be where we are with 33 points is obviously sensational," said Hecking after Friday's 2-1 defeat at Dortmund.

Forwards Alassane Plea and Thorgan Hazard, with nine goals each, are at the heart of Gladbach's success, while a robust defence has led to a perfect record of eight home league wins.

Gladbach romped to a 3-0 victory at Bayern in October, but then showed frailties at the back in a 3-1 defeat at Freiburg and a shock 5-1 drubbing at home to Leverkusen in the German Cup.

Razor-sharp Werner

RB Leipzig are fourth, on course for a Champions League return after a season's absence, with Timo Werner playing a key role.

The 22-year-old was lethal in front of goal in Saturday's 3-2 win at home to Werder Bremen, pouncing on a terrible backpass before rounding the goalkeeper to clinically slot home his chance.

It bumped his league goals tally to 11 in 2018/19 to prove he is back to his best after Germany's dismal World Cup performance.

As part of Germany's new-look attack alongside Manchester City's Leroy Sane and Bayern's Serge Gnabry, Werner will be a key factor when the Euro 2020 qualifiers start in March.