Hernandez, who spent a month under Postecoglou at Melbourne Victory and played against his Brisbane Roar sides, has been recalled to the national squad for the first time in two years ahead of the Socceroos clash in Sydney on Tuesday.
"I know about Ange, I know how he plays because I've played under him before so I've spoken to the coach about the style of football he likes to play," Hernandez said on Monday.
"But at the end of the day it's all about the way the Costa Rican team plays and the opportunity to come here and have a good game."
The 31-year-old vowed to make the most of his opportunity on Tuesday as he looks to grab one of the few remaining places in the World Cup squad.
He admits the chance to go to Brazil has provided extra motivation having shed six kilograms from his burly frame since joining the Wellington Phoenix.
"I'm very happy to take this opportunity, I know that probably 90 percent of the squad is already there and ready to go for the World Cup," Hernandez said.
"But I'm going to take this chance, it's a unique chance and I'm very grateful for the call-up and I'm going to use it and make sure that I get selected for the World Cup.
"There's no doubt that I wasn't 100 per cent fit. I needed to lose some weight and the opportunity to play for the national team now that they've made it to the World Cup has given me the motivation to lose some weight.
"I've lost about six kilos and I want to keep going and I'm just happy to be given the opportunity for the national team and I'm just going to keep going and keep fit."
The visitors are ranked 31 in the world and will field a near full-strength side to face the 57th-ranked Socceroos.
"Two players couldn't come because they were injured and one of them couldn't come because of personal reasons but I'm happy with the squad that I've got here for the game," coach Pinto said.
But Pinto remains wary of the Socceroos under Postecoglou and says they are a better side than recent 6-0 drubbings at the hands of France and Brazil suggest.
"We have to understand sometimes in soccer you need a bit of luck and France and Brazil scored some lucky goals," he said.
"I believe the game tomorrow is going to be different, also having a new coach and a new philosophy coming into the team I expect a tougher game tomorrow night."
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