Lionel Messi was liberated by winning last year's Copa America and is relishing his leading role in Argentina's World Cup bid, according to former team-mate Sergio Aguero.

Messi scored his ninth World Cup goal – and his first in a knockout tie – as Argentina claimed a 2-1 victory over Australia on Saturday, teeing up a quarter-final meeting with the Netherlands.

The seven-time Ballon d'Or winner's strike, a trademark left-footed finish after cutting inside from the right, also saw him surpass Diego Maradona's tally of eight World Cup goals for Argentina. Only Gabriel Batistuta (10) now has more for the country.

Messi highlighted his "beautiful" bond with Argentina's supporters after the win, but Aguero believes that is a recent development, one which came about as a result of the Albiceleste ending a 28-year wait to win the Copa America last July.

"Leo is going to do everything possible to achieve the goal that we all want," the former Argentina international told ESPN. 

"Leo is happy and content. The Copa America changed his life, it gave him life. After the Copa America, he was happy again in the national team, like when we were in the under-20s.

"He lived with criticism and lost finals for a long time. The Copa America was liberating for him."

Prior to Argentina's triumph over hosts Brazil last year, Messi had suffered the ignominy of losing four major international finals, failing to help his team over the line at the 2014 World Cup or the 2007, 2015 and 2016 editions of the Copa America.

Recalling that victory in Rio de Janeiro, Aguero said Brazil – who could meet Argentina in the World Cup semi-finals – would not relish a rematch.

"If we made it to the quarter-finals, let me be excited," Aguero said. "Do you think that Brazil wants to meet Argentina in the semi-finals? 

"Brazil has just lost the Copa America final, I think they don't want that match."