Klopp's new headache

In the 84th minute of Borussia Dortmund's demolition of Werder Bremen on Saturday, a new emotion rippled through the away fans' stand of the Weser Stadium. After nearly 20 months' absence, Nuri Sahin returned to the Bundesliga to play in the yellow and black kit he grew up in. The Dortmund fans cheered their old hero onto the pitch - the boy who grew up, starred in Dortmund's Bundesliga-conquering 2010-11 season, and then set off to take on the world. More or less.

"I had goose-bumps," the midfielder told Sky television after the game, visibly moved. "I couldn't take for granted how I'd be received today. I want to thank all my crazy fans. I don't think you get that anywhere else in the world."

Still only 24, Sahin has been on a well-documented odyssey around Europe, having failed to nail a starting place at Real Madrid and Liverpool. Now he's back at Dortmund, nominally on loan, but Klopp has an option to buy when the agreement runs out in 2014.

Diplomatic substitution

Perhaps just as significant as the man who came on in the 84th minute was the man who went off. Or rather, the man who didn't come off. Sahin replaced Sebastian Kehl, the 32-year-old club captain, a dependable veteran holding midfielder, and therefore a very different type of player to Sahin.

The man coach Jürgen Klopp didn't choose to take off for Sahin was Ilkay Gündogan, the 22-year-old tyro who has been groomed to fill the large hole that Sahin left, and who has bloomed this season into one of Dortmund's most important players. It was a political decision from Klopp, who must know that Gündogan is likely to be Sahin's most direct competitor in the coming weeks.

As if to underscore his new standing, one minute after Sahin had bathed in the crowd's adulation, Gündogan duly delivered a perfect vertical pass that set Lukasz Piszczek free on the right, and Dortmund's fifth goal was complete. It was exactly the kind of pass that Sahin had delivered countless times for Dortmund, and which put him on Madrid's radar.

Crowded midfield

Sahin predictably dismissed all talk of competition on Saturday.

"It's not like I want to push someone out," he said. "Of course, I want to play, and I will try to offer myself in training. I want to be a very, very good option for the coach. The team works, and I hope it will work even better with me, and I will do my part."

In an interview with Sport Bild magazine last week, Dortmund's chief executive, Hans-Joachim Watzke, also evaded the question of internal intrigue.

"Of course the competition might be a little more intense," he said. "But Nuri's quality, combined with his strong identification [with the club], will do us good."

But the reason that Sahin is the kind of player that Dortmund have plenty of - the wily attacking midfielder, always ready to deliver that killer pass that slices defenses open - is at least in part because they have specialized in developing them. Aside from Gündogan, there is Mario Götze, Marco Reus, Sven Bender, and Moritz Leitner, a new talent who has played for Germany's under-21 team. Götze has established a firm place in the front three, but at least one of the other three, and indeed Kehl, will conceivably have to give up his spot.

Meanwhile, Dortmund are light elsewhere. An injury to Robert Lewandowski would leave them without a decent striker (an area in which Bayern Munich are well-endowed with Mario Mandzukic, Mario Gomez, and Claudio Pizarro), and the absence of either Piszczek or Marcel Schmelzer invariably leaves Klopp's side exposed on one side of the defense or the other.

Klopp's options

Not that this means it was a bad idea to bring Sahin back, but Klopp's embarrassment of midfield riches will now leave him with a weekly headache. Starting Sahin and Gündogan together in a 4-2-3-1 (with that pair as the "2") could leave the back four vulnerable. That means leaving one out, or replacing one with someone more defensive like Kehl or Bender.

Then again, the other option would be to bolster the back of midfield with a third man, and play Sahin and Gündogan together in a 4-3-3 formation. This is a model that Klopp has tried against formidable opposition to some effect this season - in the 1-1 draw away at Bayern and the 1-0 victory over Manchester City.

All this, of course, presupposes that Sahin has not lost his prowess on his travels. He is sorely short of match practise, and perhaps will need to regain confidence. But then the Dortmund crowd will help him there.