World champions Italy meet Egypt at Ellis Park in Johannesburg, while Brazil meet the United States at Loftus Versfeld in Pretoria and victories for the heavyweights will ensure qualification for the semi-finals.
Brazil needed a last minute penalty to overcome Egypt in a seven-goal thriller in Bloemfontein on Monday, a narrow escape their coach Dunga blamed on fatigue.
Brazil had played two World Cup qualifiers against Uruguay and Paraguay in the preceding week and then travelled to South Africa before the meeting with the Egyptians.
But there is little respite with Thursday's game just three days after their 4-3 victory against Egypt.
Dunga has cautioned his players against a repeat performance against the Americans but also praised their fighting spirit.
"What pleased me most was the fact that we kept going until the end, trying to score the winner."
Italy had to overcome a half-time deficit before they beat the Americans 3-1 in Pretoria on Sunday.
Although the 2006 World Cup winners dominated the second half, Italy coach Marcello Lippi highlighted several concerns as he looked ahead to the match against Egypt.
"I was surprised by the tension in our game early on but we finally managed to get the ball moving, though the ball possession was not as much as I would have liked," he told reporters.
Lippi said he was well aware of Egypt's potential, having watched them closely when in Cairo three years ago at the African Nations Cup finals.
"Their players have good technical skills. I like their coach and his way of doing things."
Egypt, who lost a World Cup qualifier in Algeria just before the Confederations Cup, found a lost spark against Brazil and will likely come out with renewed confidence.
Coach Hassan Shehata told reporters on Wednesday he was still confident of progressing to the semi-finals, though that was only feasible if they beat the Italians.
