Dare to (take on) Zlatan? Well, Ulf Karlsson has.
The former Swedish athletics doctor has accused the 34-year-old of doping during his time with Juventus.
Karlsson was speaking at the Varmland historical societies sports cafe in Karlstad when he made the accusation as reported by local news agency NWT.
More from FoxSports
"Zlatan put on 10 kilos in six months during his time at Juventus," Karlsson reportedly claimed.
"I think he was doping, that's how it seems to me. I am convinced of it."
Karlsson also singled out one of Ibrahimovic's Swedish teammates at the Serie A champions: "Albin Ekdal went up eight kilograms in the same club. I believe that culture lived on Juventus at the time. They had a doctor who had previously been suspended for 22 months."
Ibrahimovic's longtime agent Mino Raiola hit back at the doping claims against his client and now says that they will take legal action against Karlsson for defamation of character.
"We will sue him," Raiola told Swedish paper Expressen.
"There are always people who hate. Maybe he is a former athlete who failed, or maybe he's just jealous. But this man has made a big mistake. He had one life before making this statement, and he will have a different life after it. He is spreading falsehoods."
"Doping at Juventus was over when Zlatan arrived. We had plenty of doping controls there and Zlatan was tested between 15 and 20 times. Juventus were always under the microscope," Raiola said.
"The claims are just crazy and the facts are not there. All the clubs Zlatan has been at know he doesn't even take aspirin."
Ibrahimovic played with Juventus for two seasons in 2004 and 2005 winning two Serie A titles before the club was stripped of the trophies for their role in the Calciopoli match-fixing scandal and relegated to Serie B.