Borussia Dortmund will still pose a threat to Bayern Munich when the rivals meet in the Bundesliga on Saturday, despite their four-match losing streak, Bayern captain Philipp Lahm believes.

Having finished second to Bayern in the league for the last two years, Dortmund have endured their worst start to a league season for 27 years and are 15th in the table with just two wins from their opening nine games.

In contrast, Pep Guardiola's Bayern are four points clear and unbeaten as they prepare to host their rivals in Germany's 'Klassiker' at Munich's Allianz Arena with 14 points separating the teams.

Both Dortmund and Bayern top their respective Champions League groups with three straight wins, but after Dortmund romped to a 3-0 league win at Munich's Allianz Arena in April, Lahm is taking nothing for granted.

"It's a meeting between two sides that have spent the last few years contesting the title," he said.

"Dortmund have shown their true selves in the Champions League with nine points from three games.

"They're a real threat to us."

Bayern beat Dortmund 2-0 in May's German Cup final in Berlin the last time the teams met, but Borussia romped to a 3-0 win in Munich in their last league meeting.

Dortmund captain Mats Hummels described the Bayern game as a "tasty task".

"If there is one game when we can get some self-confidence, it's the game against Bayern," said Hummels.

And veteran midfielder Sebastian Kehl says Dortmund can win in Munich, providing they shake off their lack of league goals, having scored just four in their last six Bundesliga games.

"We have always looked good against Bayern and we can again, if we play compact and have a bit of luck," said Kehl.

"But most of all we must have the will to score a goal in the league."

Borussia warmed up for their trip to Munich by beating Hamburg's St Pauli 3-0 away in the second round of the German Cup.

"The victory was important for Saturday, we want to annoy Bayern," said Dortmund's Germany international Kevin Grosskreutz.