Bayern Munich restart their charge for an eighth straight Bundesliga title at Union Berlin on Sunday amid doubts the Bavarian giants will be able to last the distance after a two-month hiatus.

Hansi Flick's side hold a slender one-point lead at the top of the league heading into their trip to the German capital, which has been the scene of some impressive upsets thanks to promoted Union's form at their Alten Foersterei stadium.

Union have twice shocked the league leaders this season, beating Borussia Dortmund 3-1 in August and turning out 2-0 victors over Borussia Moenchengladbach three months later.

Now it's Bayern's turn.

Bayern flew up to Berlin by private jet from a military airport in Ingolstadt, near Munich, with the two team buses allowed to drive directly onto the tarmac.

The players and Flick's backroom staff tested negative for the coronavirus -- for the fifth time -- and the squad all wore face masks for the brief flight.

Flick is unsure of his team's ability to play out a full match after having only received the go-ahead to resume team training last week.

"We don't know if the team can hold out over 90 minutes," said Flick.

"We have to just deal with the situation."

The Bundesliga is the first major league in Europe to return to action since the coronavirus brought football to a halt two months.

The restart was only possible thanks to a host of strict health regulations, such as near-empty stands in what are usually passion-filled stadiums and regular testing for the virus.

That means Union won't be able to count on their ferocious home support at their ground in east Berlin on the outskirts of the German capital.

They will also be without their coach Urs Fischer after breaking the team quarantine following the death of his father-in-law.

"It's not possible to surprise Bayern with the experience their players have," said Union assistant coach Markus Hoffmann, who is in charge against Bayern.

"They've already experienced everything.

"We have to concentrate on ourselves and try to implement what we can to influence the game in the best possible way."

Bayern's lead was cut to a single point by Borussia Dortmund, who on Saturday showed no ring rustiness in a 4-0 demolition of Ruhr rivals Schalke.

Norwegian sensation Erling Braut Haaland, 19, scored the first Bundesliga goal after the restart and set up Raphael Guerreiro for the first of his brace.

As well as the echoing arenas, a host of other rules have been put in place to try to stop the spread of the virus, from frequent testing to masks for players on the subs bench and a week-long quarantine for teams ahead of the restart.

However, advice to socially distance didn't stop Hertha Berlin players from celebrating their goals in a 3-0 win at Hoffenheim by hugging each other.

"The fact is that this is part of football," said Hertha coach Bruno Labbadia. "We've been tested so many times that we can allow it.

"If you can't celebrate anymore, the whole thing breaks down."

A German Football League (DFL) spokesman confirmed there will be no punishment, as it had only offered "guidelines" on how goals should be celebrated.

However senior politician Markus Soeder, the state minister for Bavaria, said Sunday that he expects Bundesliga bosses to "tighten up" the hygiene guidelines after Hertha's hugs in Hoffenheim.

The DFL has also made no secret of the fact that several clubs are in a dire financial situation as a result of the lockdown.

If they are able to complete the nine remaining rounds of matches by June 30, clubs could receive around 300 million euros ($324 million) from television contracts.

Clubs in England, Spain and Italy, where leagues are weeks away from returning, will be watching to see how the rest of weekend goes.

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BORUSSIA DORTMUND