Germany international centre back is suffering from flu.

Borussia Dortmund head coach Jurgen Klopp says that key central defender Mats Hummels is still a major doubt for Wednesday night’s Champions League encounter with Shakhtar Donetsk.

The two clubs drew the first leg of their last 16 match up in Ukraine 2-2, although only after Germany international Hummels himself rose powerfully to head home a late equaliser that puts the Bundesliga champions in the driving seat going into the return encounter in Dortmund.

Klopp says that no final decision will be made about the 24-year-old’s fitness until after the team have trained on the morning of the game, with Hummels suffering from a bad bout of flu.

The highly skilled defender has already been forced to sit out Dortmund’s 1-0 German Cup loss to arch rivals Bayern Munich last Tuesday night, as well as Saturday afternoon’s subsequent 3-1 home win in the Bundesliga against Hannover 96.

“I have read that if we lose this game it’s a lost season, I find that a bit hard to swallow,” said Klopp in his pre-match press conference – viewable on the video below.

“We still have the chance to finish second in the Bundesliga, which we could have only dreamed about a few seasons ago.

“It’ll be difficult for both teams, we have a slight advantage, but we can’t take anything for granted.”