Borussia Dortmund will carry forward the energy instilled by Mike Tullberg under new coach Niko Kovac, sporting director Sebastian Kehl has promised.

Tullberg took over as interim head coach after Nuri Sahin was sacked last month, amid a poor run of results that saw Dortmund tumble into the bottom half of the Bundesliga table.

After confirmation that former Bayern Munich boss Kovac would take over from Sunday, Tullberg ended his spell in the dugout with a 2-1 win at Heidenheim on Saturday.

Speaking to reporters in the mixed zone after that game, Kehl thanked Tullberg and his staff for changing the mood at the Westfalenstadion.

"We have now picked up four points in the league, even though we were outnumbered for 70 minutes in the 2-2 draw with Bremen a week ago," Kehl said.

"We deserved to win today, even if there were phases in the second half in which things were a bit more unsettled. The goal for 2-1 was unnecessary. Nonetheless, the team put up a fight. 

"The three points will do us a world of good. We're still in the mix. It's extremely tight in the table. 

"The coaching staff have tried to be positive and to give the team energy. We've earned the results. A bit of the lightness came back too. 

"But the path must remain the same, and it will not change under Nico Kovac. We need to work hard on ourselves and earn the results. It's all still to play for."

Serhou Guirassy and Maximilian Beier were on target in Saturday's win, with the former also having netted twice in Wednesday's 3-1 Champions League victory over Shakhtar Donetsk.

He is the joint-leading goalscorer in this season's Champions League alongside Robert Lewandowski (nine goals) and has struck in four consecutive Bundesliga matches. 

Tullberg, who first joined Dortmund as head coach of their reserve team in 2019 before coaching their under-19 side, appeared emotional at the final whistle on Saturday.

As Tullberg prepares to return to that role, he said: "The club means a lot to me. 

"You can see that emotional outbreak at the under-19 matches as well, but not too many people watch those!

"It does not matter in which role, I am just happy to be able to work at Borussia Dortmund."

Dortmund are now 10th in the Bundesliga table with 29 points from 20 games, four adrift of the top four.