The Germany international has missed just two Bundesliga games this season, most recently due to a bout of flu. That virus also prevented him from facing his former club FC Bayern Munich in the quarter-finals of the DFB Cup, and the 1-0 defeat in that game was partly put down to his absence.
"The worst news"
While Dortmund's chances of making up a 20-point deficit on Bayern in the Bundesliga look nigh on impossible, the loss of their defensive coordinator remains a serious blow to their declared season objective of second place in the standings - on top of which there is the small matter of the UEFA Champions League to consider.
could miss both legs of next month's quarter-final, against opponents to be revealed in Friday’s draw. “This is bitter news - the worst news we could have got,” head coach Jürgen Klopp told Sky television after hearing the prognosis. “It didn’t initially look that bad, but unfortunately it clearly was.”
In Hummels' absence has done a more than decent job partnering Neven Subotic in the centre of the defence recently, not least when he opened the scoring in the home Champions League victory over Shakhtar Donetsk. That notwithstanding, Hummels is not so easy to replace and not only on account of his defensive capabilities.
With 24 shots on goal, he is the most attack-minded centre half in the league, and his threat from corners is unrivalled among his defensive colleagues. He scored from one such set piece against Bayer 04 Leverkusen, and nabbed the all-important late equaliser at Donetsk last month as well.
Pros and cons
That said, Santana in his stand-in capacity has won 69.7 per cent of his one-on-one challenges, compared to Hummels' 62.2 per cent season average. When it comes to aerial jousting, the 26-year-old Brazilian also has the edge (70.9 per cent as against 68.1 for Hummels), and although he has only had half as many attempt on goal, his total time on the pitch of 827 minutes has been far less than that of his injured team-mate (1935).
What Dortmund will undoubtedly miss however is Hummels' precise, game-opening plays out of defence. His 139 long balls forward well outstrip Santana's 35. On the other hand, they may gain from the latter's dynamism, as demonstrated by an average of over 10km covered per match, and 15 sprints completed, compared to Hummels’ average of 9.5km and nine sprints.
Subotic to the fore
Since Hummels arrived at Dortmund from FC Bayern, initially on loan, in 2008, he has missed just nine Bundesliga games. BVB lost only one of those, though, winning six and drawing two. Clearly, they can prosper without him. Nonetheless, his absence undoubtedly puts a greater onus of responsibility on , who even as it stands is the Dortmund player seeing the most of the ball on average. One way or the other, the Yellow-Blacks will certainly need both him and Santana on top form over the weeks ahead.