Luis Suarez told FIFA's disciplinary panel that he did not deliberately bite Italy defender Giorgio Chiellini at the World Cup.
The Uruguay striker's defence that he lost balance and fell on his opponent will now be presented to FIFA's appeal panel, after his national federation notified FIFA late Friday it would challenge the nine-match, four-month ban.
"In no way it happened how you have described, as a bite or intent to bite," Suarez wrote in Spanish in a letter dated June 25.
The player's defence is in paragraph 6 of FIFA's disciplinary committee ruling, which has been seen by The Associated Press.
"After the impact ... I lost my balance, making my body unstable and falling on top of my opponent," Suarez wrote in his submission to the panel which met Wednesday, one day after Uruguay beat Italy 1-0 in a decisive group-stage match.
"At that moment I hit my face against the player leaving a small bruise on my cheek and a strong pain in my teeth," Suarez said.
However, the seven-man panel which met on Wednesday evening dismissed the argument.
The bite was "deliberate, intentional and without provocation," the ruling stated in paragraph No. 26 of the panel's conclusions.
Suarez was banned for nine Uruguay matches and four months from all football. He was also fined 100,000 Swiss francs ($120,000).
The panel, chaired by former Switzerland international Claudio Sulser, included members from the Cook Islands, Hong Kong, Pakistan, Panama, South Africa and Singapore.
On Saturday, FIFA confirmed that formal proceedings had begun to challenge the longest ban for a World Cup player in 20 years.
"We have a declaration that they are planning to appeal," FIFA spokeswoman Delia Fischer said. The Uruguay federation now has seven days to submit written grounds for the appeal.
Back in Montevideo, Suarez has been welcomed home as a hero by Uruguay fans.
"I'm writing this message to express thanks for the outpouring of support and affection that I'm getting. Both me and my family really appreciate it," Suarez said Saturday on his Twitter account.
"Thank you very much for being on my side and I want all of us to support our teammates today in the match against Colombia," he wrote, ahead of Uruguay's Round of 16 match at Maracana Stadium in Rio de Janeiro.
Hola a todos, escribo este mensaje para dar las gracias a todas las muestras de apoyo y cariño que estoy (cont) http://t.co/2uo0LXaqs2— Luis Suarez (@luis16suarez) June 28, 2014