Mats Hummels couldn't contain his fury. As Kai Havertz rattled home a nerveless penalty that settled this tie at the second attempt, the veteran defender stormed down the touchline in an attempt to control the rage he'd unleashed at the fourth official.

The retake was, though unusual, technically correct. But the handball that preceded it was, in the eyes of the perpetrator, very much not.

"It was so close to me that it just can't be [a handball]," Dortmund's Marius Wolf told DW after the game. "We feel very bitter about how the referee officiated the game and it's a real shame. We have to let it go but it's very bitter."

He and Hummels were not alone. Their teammate Emre Can called the referee "arrogant" while Jude Bellingham and coach Edin Terzic also expressed their disappointment as the two-legged tie became dominated by those two moments, and two minutes, in the Dortmund penalty box.

German frustrations were just as clear in the stands and on BVB's social media channels, as the Bundesliga side saw their perfect 2023 fall away and another year pass by without a Champions League run to get excited about.

Penalty crucial but Chelsea on top

In truth, the perfection they'd recently attained with 10 wins in 10 games in 2023 had been slipping from their grasp for most of the night. From the opening moments, Chelsea, led by an elusive, inventive front three of Havertz, Raheem Sterling and Joao Felix, threatened constantly. Havertz rattled the bar, Felix found space in crowds and Sterling, eventually, slammed home the opener after a miskick just before half time.

The frustration evident in Terzic and his side would later start to give way to disappointment colored with a little perspective. Though they may not have been expected to pass this stage of the competition at the end of 2022, ten straight wins tends to raise expectations.

"We shouldn't be ashamed to lose to Chelsea," Terzic said after the game.."We had quite a few chances and couldn't force it in. Chelsea probably deserved it over the two legs but we could have progressed as well."

Considering the expense, if not the form, of the side they were facing, Dortmund's response to going down in the tie was wholehearted enough. But without the outlet of Karim Adeyemi's pace, they struggled to get in behind the Premier League side, who put in their best performance in some time.

Chelsea looked sharper, smarter and better-organized, if a little wayward in the final third. The absence of regular keeper Gregor Kobel also hurt Dortmund, who weren't as calm and disciplined as they've been in the latter stages of their recent run, with Chelsea also controlling the midfield. 

"The last two weeks were hard, we lost a lot of games," Havertz said. "Tonight was important. This is a big tournament and it's the last trophy that we can win. We showed character and that we want to keep going."

Dortmund face tough challenges ahead

The defeat to Chelsea aligned with the early loss of Julian Brandt to an ankle injury are significant challenges to a Dortmund side and coach who have been riding the crest of a wave until now. After a patchy start in the Bundesliga, they've snuck up on the rails. But with a trip to rivals Schalke on Saturday followed by games against Cologne, Bayern and, in the cup, RB Leipzig, it is Dortmund's reaction to this defeat, rather than the loss itself, that could prove more crucial.

Wolf said that, although emotions were clearly running high after the match, he had every faith they would not define the rest of their season. "The day after tomorrow we're thinking only of Schalke and we want to win the derby at all costs. We have to put our focus on winning that and all the games after it."

That much is clear. Questions about mentality have hung around the neck of Dortmund players since long before Terzic took control. Though winning runs quiet them, it's likely only winning trophies will see them silenced.

In west London on Tuesday, a chance to win one, albeit the least likely, was spurned. However, like Havertz, Dortmund may yet get another.

Edited by: John Silk