Borussia Dortmund captain Mats Hummels has warned the club's players not to get carried away by their 100 percent start to the season.
Dortmund have been revitalised under new coach Thomas Tuchel after a difficult time last season and top the Bundesliga table on goal difference from Bayern Munich.
But Hummels told a news conference: "We also started with five wins two years ago -- and suddenly were 15 points behind [the leaders] in December."
Despite scoring 18 goals in those five opening league games, seven of them against Champions League sides Borussia Monchengladbach and Bayer Leverkusen, Germany international Hummels said things could easily go wrong.
"Right now, it is just important for us to create a cushion of points on the perceived competitors for the Champions League spots," he added.
Prior to Dortmund's meeting with Bayern at the Allianz Arena early next month, they take on strugglers Hoffenheim and newly-promoted Darmstadt.
And the skipper looked ahead to the Bayern clash, saying: "They have also won all of their games -- both teams are on a very high level."
The 26-year-old added that Borussia would "have to see" how they performed against Bayern. "We might be able to say more after that," he said.
Hoffenheim have taken only one point from their first five games of the season -- but Dortmund will not be cheered on by their usual full contingent of travelling supporters on Wednesday because of a boycott over ticket prices.
They are being asked to pay €55 because the game is ranked in the top category, €30 more than fans of clubs including Augsburg will have to pay for the same seats.
Marc Quambusch, who has organised protests against price hikes in German football for over five years, told ESPN FC that 500 tickets had been returned to Hoffenheim by Dortmund.