Neymar, 26, was tipped to lead Brazil to a record sixth World Cup title this month to heal the wounds of the 2014 failure on their home turf - in which the nation was scarred by a 7-1 humbling by eventual champions Germany.
While his participation was in doubt for months due to a foot injury picked up during club duty with Paris Saint-Germain, the attacking talisman recovered in time for the global showpiece to create major optimism in his homeland.
However, the Selecao fell to Belgium in a 2-1 defeat on Friday, in a pulsating last-eight encounter, while the prolific forward was unable to inspire the South American giants to victory.
"I can say this is the saddest moment of my career," he wrote on his official Instagram account.
"The pain is very great because we knew we could get there. We knew we had the conditions to go further and make history.
"It is difficult to want to find the strength to want to play football again, but I'm sure God will give me enough strength to face anything.
"I'll never stop thanking God, even in defeat, because I know that your way is much better than mine.
"Very happy to be part of this team, I am proud of all."
Neymar has scored 57 goals in 90 games for Brazil since making his debut for the national side in 2010.
Posso dizer que é o momento mais triste da minha carreira, a dor é muito grande porque sabíamos que poderíamos chegar, sabíamos que tínhamos condições de irmos mais além, de fazer história .. mas não foi dessa vez. Difícil encontrar forças pra querer voltar a jogar futebol, mas tenho certeza que Deus me dará força suficiente pra enfrentar qualquer coisa, por isso nunca deixarei de te agradecer Deus, até mesmo na derrota... porque eu sei que o teu caminho é muito melhor do que o meu ????????❤️ Muito feliz em fazer parte desse time, estou orgulhoso de todos, interromperam nosso sonho mas não tiraram da nossa cabeça e nem dos nossos corações ????????❤️ . . . ???? @nogueirafoto