BERLIN — Erling Haaland’s sensational start only papered over the cracks at Borussia Dortmund.

The 19-year-old Haaland scored a hat trick in his debut in only 23 minutes. He racked up seven goals in his first three games. But the tall Norwegian striker was held scoreless for the first time on Saturday as Dortmund slumped to a 4-3 loss, hurting the club’s Bundesliga title bid.

It wasn’t Haaland’s fault — the team’s problems are at the other end of the field.

Dortmund was leading 3-2 at Bayer Leverkusen but conceded two goals in 81 seconds, only days after it was knocked out of the German Cup in a 3-2 loss at struggling Werder Bremen.

“When you concede so many goals and put yourself in such stupid positions, you can’t win games,” Dortmund player-manager Sebastian Kehl said. “The third goal was deserved, we had the game under control, but then we were way too passive. We have to keep doing well going forward and defend together. It’s not only a problem for defenders. It’s about all the work when we don’t have the ball.”

Dortmund’s work with the ball is fine. The team has scored 19 goals in four Bundesliga games since the midseason break. Along with Haaland, the team boasts an impressive attacking lineup in Marco Reus, Julian Brandt, Jadon Sancho, Thorgan Hazard and emerging talent Giovanni Reyna. World Cup winner Mario Gotze has remained mostly an unused substitute on the bench.

But mistakes in midfield and defense have been costly all season. Manuel Akanji, Mats Hummels, Raphael Guerreiro and Axel Witsel were at fault against Leverkusen, though no Dortmund player is blameless over the whole season.

Dortmund has already conceded 32 goals in 21 league games — a lot more than any of its title-chasing rivals.

Dortmund coach Lucien Favre has tried variations from his favored 4-3-3 formation, switching at times to three defenders with two wingers dropping back to help out, but the issues remain.

“We’re not closing down crosses. We’re not attacking the ball. We’re not decisive enough defending in the penalty area,” Dortmund sporting director Michael Zorc said. “We’ve had these problems for a while. That’s the main reason we’re not higher in the table.”

Dortmund signed Germany international Emre Can from Juventus to help ease its defensive worries. The 26-year-old Can scored a brilliant goal in his debut against former club Leverkusen but was in no mood to celebrate.

“That’s not how you win games,” Can said of conceding the two late goals. “The team has a lot of potential but has to learn one thing — when you go in front, you have to play dirtier.”

Dortmund can be grateful that the top two — Bayern Munich and Leipzig — held each other to a scoreless draw on Saturday. Dortmund remains third, four points behind Bayern, which leads Leipzig by a point.

But the next games could be decisive for Favre. Dortmund faces a tough game against Eintracht Frankfurt at home on Friday before it welcomes Paris Saint-Germain and former coach Thomas Tuchel for a reunion in the last 16 of the Champions League next Tuesday.