The Benfica striker collected an impressive 34 goals for Benfica to help them win the Portuguese league last season, but he will never produce a more crucial goal for his country.
Cardozo demonstrated all the hallmarks of a cold-bloodied killer to cause coach Gerardo Martino to weep openly with joy, while the whole of Japan shed tears of bitter disappointment.
It needed the first penalty shoot-out of the finals to separate the two teams after two hours of the most mind-numbing encounter served up in South Africa over the last three weeks.
It was the first time either side had ever had to suffer the nerve-shredding experience of a shoot-out after barely creating a chance in open play.
And it was the Blue Samurai who cracked first in the spot kicks with Yuichi Komano discovering just how painful it is to be the unfortunate culprit known as the man who let his country down.
The Japanese defender ended Takeshi Okada's dream of taking his side to the semi-finals on behalf of the whole of Asia when he smashed his spot kick off the cross bar after team mates Yasuhito Endo and captain Makoto Hasebe had held their nerve.
But Cardozo, who has barely been used in the finals by Martino swaggered up to roll home his spot kick and deceive Japanese 'keeper Eiji Kawashima to spark scenes of wild delight among his team mates.
Both teams were on a roll, having not been expected to get into the last 16, but instead of riding their luck, they were gripped by fear for large periods and penalties always looked like the only way to split the two sides.
The chance of entering unchartered territory of the quarter finals seemed to hang like lead weights around the necks of both sets of players.
There was no sign of the adventure Japan showed to beat Denmark in their final group game to ensure progress from the group stage.
Only in fleeting first half moments did they threaten and give Paraguay 'keeper Justo Villar any awkward moments.
The most dangerous came when Daisuke Matsui let fly from fully 30-yards to try to beat the keeper, only to see his shot crash back off the crossbar.
Keisuke Honda wasted another chance, firing wide from the edge of the area and Paraguay were equally disappointing and a shadow of the attacking side that roared into the final 16.
Lucas Barrios had their two best chances, but was twice denied by Kawashima as both sides increasingly seemed willing to accept their fate from spot kicks.
After three previous failures to make the last eight, and the agony of losing to the first ever golden goal from Laurent Blanc in France '98, Paraguay will have to improve drastically if they are to make the semi-finals.
Paraguay (4-3-3): Villar; Morel, Da Silva, Alcaraz, Bonet; Ortigoza (E Barreto 75), Vera, Riveros; Barrios, Santa Cruz (Cardozo 94) Benitez (Valdez 60).
Subs not used: Veron, Caniza, Cardozo, Santana, D Barreto, Torres, Bobadilla, Gamarra, J Caceres.
Japan (4-5-1): Kawashima; Komano, Nakazawa, Tanaka, Nagamoto; Abe (K Nakamura 80), Endo, Matsui (Okazaki 65), Hasebe, Okubo (Tamada 105); Honda.
Subs not used: Narazaki, Uchida, S Nakamura, Yano, Iwamasa, Konno, Morimito, Inamoto, Kawaguchi