Dortmund face Chelsea with faith in 'final puzzle piece' Haller

Dortmund, who limped into the winter break with two straight losses to fall nine points behind leaders Bayern Munich, come into the clash with six wins on the trot, having cut Bayern's lead to just three.

Crucial to this resurgence has been the return of several of the club's key players from injury, not least star summer signing Sebastien Haller, who missed the first half of the season battling testicular cancer.

"He's a piece of the puzzle that we've unfortunately been missing for a long time," said sporting director Sebastian Kehl on Monday.

"A fit Sebastien Haller not only enriches our team with his profile, but also with his personality.

"We have waited longingly for him, he has been working towards this for a long time... we're happy that he's back, and so is he."

Haller, 28, was signed to channel the club's array of young, attacking talent - each of Youssoufa Moukoko, Karim Adeyemi, Jamie Bynoe-Gittens, Gio Reyna and Jude Bellingham are 21 or under - into goals.

While the Ivory Coast striker, who underwent two operations and four bouts of chemotherapy, admits he is not back to full fitness just yet, Haller has already demonstrated his maturity and vision up front.

There was no better example of this than in his Dortmund starting debut at Leverkusen in late January, where he expertly let a cross run through his legs to an unmarked Adeyemi who scored his first league goal.

Europe 'is his stage'

Dortmund know all too well the damage Haller can do on European nights.

The former Ajax striker scored two and assisted two more against Dortmund in the clubs' group stage fixtures in last season's Champions League, on his way to chalking up 11 goals in eight appearances.

"The Champions League is his stage" Kehl said on Monday, recalling "the games against Ajax where he hurt us a lot."

"I hope that he can put in a really good performance again on Wednesday and, above all, I hope he stays healthy in the long run."

Manager Edin Terzic on Saturday sought to emphasise the quality of the squad at his disposal, including those who may be straddling the bench.

"There are guys who start the game for us, guys who finish the game for us and guys who decide the game for us," Terzic said.

Their opponents on Wednesday also boast a squad of incredible quality, although Chelsea's recent run has been anything but stable.

The spending spree at Stamford Bridge, which Kehl called "wild", sent shockwaves across the continent, even among Europe's biggest spenders.

As yet, splashing the cash has failed to yield an on-field turnaround, with the club having won just one of their last eight matches in all competitions.

Hopefully 'seven in seven'

The sides' contrasting fortunes has meant Dortmund have surprisingly been given favourite status by some pundits and bookmakers.

Dortmund midfielder Julian Brandt spoke of the "euphoria" running through the team after the sixth straight win, while Kehl said the side had shown "we are a force to be reckoned with."

As has happened more and more often on the pitch recently, Dortmund's 19-year-old midfielder Bellingham on Saturday urged calm among his teammates and quickly turned their focus to Wednesday's match.

"There's no point looking at the run to be fair, as soon as you finish one game and get the right result, you need to move on and focus on the next one," he said.

"Six in six (in 2023) in all competitions. Getting ready for Chelsea now and hopefully we will be going for seven in seven.

"As soon as you've got a run going, you don't want to be looking in the past."