The Kiwi underdogs will have talismanic striker Chris Wood available to play from the start after a tight hamstring limited him to a role off the bench in the first-leg in Wellington.
Peru is trying for its first berth since 1982, and its fifth overall.
New Zealand are $5.50 outsiders at the TAB to advance to their third World Cup. New Zealand has only qualified twice, the last time coming in 2010 in South Africa.
"I'm sure they're going to stay back", said Gareca, an Argentine who has transformed Peru's national team into the 10th-ranked team in the world. "We know if Peru loses it will be a national disaster and we don't have that sort of pressure", Hudson said in Spanish.
Peru hope to join four other South American teams that have already qualified for next year's tournament: Brazil, Argentina, Colombia and Uruguay.
Farfan, who plays his club football for Russian outfit Lokomotiv Moscow, will be Peru's chief attacking threat in the absence of Paolo Guerrero, who is provisionally banned for failing a doping test. He also missed the first leg.
The streets in the Peruvian capital are all decked out in the red and white of the team's colors.
It's reported to be 100 meters long and took fans weeks to stitch together.