Peru captain and striker Paolo Guerrero has been provisionally suspended by FIFA for 30 days after failing a doping test.
Guerrero tested positive on Oct. 5 after the World Cup qualifying match against Argentina, the Peruvian Football Federation added on Friday.
The federation did not disclose the banned substance.
If the decision is upheld, Peru will miss its main striker for both World Cup playoff matches against New Zealand this month. Peru and New Zealand meet on Nov. 11 and 16.
The federation said it "believes the facts will soon be clarified and this issue will be permanently solved."
Guerrero, who plays his club football for Flamengo, scored six times in South American qualifiers and led Peru to fifth place.
Earlier Friday, the head of doping control of the Brazilian Football Confederation said Guerrero could still provide evidence that he did not take prohibited substances without warning Peru and Flamengo.
"If Guerrero has justification for this and that justification was offered before the match against Argentina, it is not a doping case," Fernando Solera told channel SporTV.
Solera also said Flamengo showed evidence that Guerrero did not take any illegal substances during his time with the Brazilian club.