Germany's 7-1 victory over Brazil in Tuesday's World Cup semifinal was a historic, emphatic result that could not have come at a better time.
The Nationalmannschaft had labored through most of the tournament until that point, progressing in a somewhat unconvincing manner. The way they hammered the hosts breathed huge confidence into Joachim Low's side. But it may have come at a price.
Mats Hummels was forced off the pitch at halftime with a knee injury that was later confirmed to be an aggravation of a previous ailment.
The defender was substituted in the second half of Germany's group-stage opener with Portugal. Although he was pronounced fit for the next encounter, with Ghana, it was confirmed after the Brazil match that he had re-injured his knee.
Germany team spokesman Jens Grittner confirmed that Hummels suffered from tendinitis, according to a report by Oliver Todd in the Daily Mail.
Team manager Oliver Bierhoff nonetheless was confident that the 25-year-old would be able to play in the final: "[Hummels' substitution was] a precautionary measure," he said. "We assume he'll be able to play in the final."
If Hummels is unable to play in Sunday's match, however, Low will have to determine the best way to cope in his absence. And indeed, there are a few options.
The most likely scenario for Low is to reinstate Per Mertesacker in central defense alongside Jerome Boateng. The two played together against Algeria, albeit unconvincingly. Manuel Neuer repeatedly had to come off his line to bail out his defenders, making 21 touches of the ball outside the box, as reported by Jonny Singer in the Daily Mail.
The last-16 clash was one of only two matches in which Germany conceded, the pace of the Algerian forwards getting the better of the slow Mertesacker.
Ghana's pace also exposed the Arsenal man in the group stage in a match that ended in a 2-2 draw. And after he came on for Hummels against Brazil, the German defense began to unravel.
Germany's defense is rather strong even with Mertesacker, who has 103 caps. He is exceptionally clean in the challenge and has enough game-reading skill to make up for his lack of pace.
But the fact that all four of Germany's goals conceded have come in his 434 minutes on the pitch suggests that there may be a better option for Low.
With Shkodran Mustafi ruled out of the tournament with a muscular injury, the only option on the bench is Matthias Ginter. The 20-year-old is enormously talented and in all likelihood will be a permanent fixture in the German squad from this point forward. But he is Germany's youngest player at the World Cup and is largely inexperienced.
With just one cap and no experience in the Champions League, it would be a huge risk for Low to throw the Freiburg man into the proverbial deep end—especially against arguably the best forwards Germany will have faced at the World Cup.
There is a third possibility for Germany, that being to move Benedikt Hoewedes from left back to central defense.
Low has already moved one of his full-backs to the center, putting Boateng in interior defense and displacing Mertesacker. And Hoewedes has, after a shaky start to the tournament, convinced at left back. He would probably be more reliable still in his natural, central position.
The downside to moving Hoewedes into a central role is that Low would have to introduce a new left back. Whereas Boateng was put in central defense to accommodate right back Philipp Lahm, Low has no proven left-sided option available.
Kevin Grosskreutz and Erik Durm are possibilities, but the former is a converted winger who has 113 minutes' experience as a right back on the international stage. The latter is a converted forward with even less experience, a backup at club level who only played left back for Germany in one 85-minute appearance.
Both Durm and Grosskreutz have potential to be quality, reliable full-backs, but if Low had any intention to use either during this World Cup, they would have made an appearance by now. As with Ginter, it would be a huge risk to introduce either to play his first World Cup minutes in a final.
No matter whom Low decides to start, Germany will be at a big disadvantage if Hummels is unable to play.
Whether with an inexperienced left back or center back in Durm, Grosskreutz or Ginter, or with a slower option in Mertesacker, the Nationalmannschaft will have their weaknesses and will not be the same without the Dortmund defender.
Between now and Sunday, Low and Germany fans alike will be sweating over Hummels' fitness.