The Swedish striker suffered a cruciate injury in the Europa League tie with Anderlecht, but no official information has been provided about the timescale of his recovery.
Becke reckons that Ibrahimovic's injury might not be as serious as initially suggested.
"I have never experienced anything similar during my 35 years as a coach. It is almost comical," he told Swedish newspaper Expressen.
"I'm completely fascinated by the fact that there is no 100 percent standard diagnosis - that it has not come out yet. I don't think I have experienced it in my 35 years as a coach.
"It is a very skilled environment which can keep it quiet and not let things on, it just won't come out. It may well be that it is not so serious. It is a little exciting."