A poor run of form, which has seen Hannover fail to win any of their last five Bundesliga matches, has sucked them into the relegation battle.
Tayfun Korkut's side sit 12th as a result, just six points above the relegation play-off place, and their woes were compounded when top scorer Diouf was forced off in the first half of Saturday's 1-1 draw with Bayer Leverkusen.
Hannover later confirmed that Diouf has suffered a dislocated shoulder, but Dufner does not want to dwell on the bad news.
"Clearly this is bitter," Dufner said.
"But we can't change it. I want to hear no whining."
Dufner does not think the injury will help Hannover in their bid to keep hold of the in-demand striker, either.
"Clubs that have interest, (will) get no cold feet due to this injury," he added.
Former Manchester United forward Diouf has scored eight goals in 19 Bundesliga appearances this season.
