The 32-year-old striker, who is moving to New York City via a loan spell at Melbourne City, decided before the tournament began that he would call time on his international career upon the conclusion of la Roja's campaign in Brazil.
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"Playing for the national team has always been a joy to me," the nation's all-time record goalscorer told reporters after the game in Curitiba.
"As it's been my dream during my whole life, I would like to play for the national team until I'm 55, but I'm aware that's not possible.
"I made the decision of going to the MLS and I assume I will be kind of inactive. If the coach [Vicente del Bosque] calls me again, I will be pleased to attend, but I have to be realistic."
Villa's instinctive first-half strike against the Aussies was his 59th goal in 97 appearances for Spain.
It is a record that is unlikely to be broken any time soon bu,t, while the former Barcelona man was delighted to have added to his tally, it did not take the edge off his disappointment at seeing the reigning world champions fall at the first hurdle in Brazil.
"After the two first games against two rivals that were better than us, Netherlands and Chile, we tried to beat Australia and so we did," he mused.
"I am happy about scoring the opening goal, but we leave this World Cup feeling very sad.
"I hope that not too many years pass before someone breaks my record. It would be a source of joy to have other players beat it because if that happens, it will be good for the national team."