Peru captain and record goalscorer Paolo Guerrero will miss this summer's World Cup after having a drugs ban increased from six to 14 months.
The 34-year-old tested positive for cocaine after the qualifier against Argentina on 6 October.
Guerrero was initially banned for 12 months, but that suspension was halved by Fifa's appeal committee.
The World Anti-Doping Agency appealed to the Court of Arbitration for Sport, which imposed the 14-month ban.
Wada wanted the suspension to be increased to two years, but Guerrero also appealed in the hope it would be annulled.
Cas said the Flamengo forward had ingested a tea containing the prohibited substance.
It said in a statement: "The Cas panel confirmed the existence of an anti-doping rule violation (ADRV) committed by Mr Guerrero but also accepted that he did not attempt to enhance his performance by ingesting the prohibited substance.
"However, the panel considered that the player did bear some fault or negligence, even if it was not significant, and that he could have taken some measures to prevent him from committing the ADRV."
Former Bayern Munich player Guerrero has scored 32 goals in 86 appearances for his country.
Peru beat New Zealand over two legs in a play-off in November to qualify for the World Cup, their first appearance at the tournament since 1982.