Reigning champions South Africa play Fiji in the second match of their title defence on Saturday well aware of the threat the South Sea Islanders can pose. In the 2007 World Cup, the Fijians pulled off one of the shocks of the tournament by beating Wales to move into the quarter-finals against the Springboks. That game in sunny, hot conditions in Marseille was a humdinger of a match decided in large part by a superb covering tackle from Bok winger JP Pietersen on a tryline-bound Ifereimi Rawaqa with the score at 23-20 in the second-half. That try-saving tackle swung the momentum four years ago, the Boks running out eventual winners with two late tries, but veteran lock Victor Matfield insisted South Africa had to be ready to up their game. "They caused some problems against us in the quarter-finals four years back, we had some troubles with 20 minutes to go," said Matfield, who will miss Saturday's match with a hamstring niggle sustained in the 17-16 win over Wales. "We need to be 100 percent prepared come Saturday and that's the most important. "The Welsh really are a team that can keep ball through phases, keeping the ball. But in attack we never thought they were going to score against us. "But with Fiji, if there's a turnover, one or two passes and then they've got runners who can really hurt you. I don't think the Welsh have guys like that. They have good structures but no individuals, but these guys have individuals who can hurt you." Matfield added: "During the kicking game and turnovers, you need to be on your game in defence. "You need to be accurate. Fiji will give you a challenge if you make mistakes in your own half." Fiji put a game Namibia to the sword 49-25 in their opening match, running in six tries, but Toulon winger Gabi Lovobalavu said the Fijians had turned their thoughts directly on South Africa. "We started well last week, we had a good game but we have left it behind us and we focus now on South Africa," he said. "We know they're very big boys, very physical team and we're training hard this week to try to encounter them head on at the weekend. "They are the world champions, but we know we're going to give them a good game on Saturday." Injury-hit South Africa made six changes to the team that will face Fiji from the one that scraped past Wales. Veteran lock Bakkies Botha returns from an achilles tendon strain that saw him miss the Welsh match Odwa Ndungane takes Bryan Habana's spot on the left wing, while Pat Lambie was called up as fullback, with Frans Steyn shifting to inside centre as cover for Jean de Villiers. Butch James' place on the bench was taken by Ruan Pianaar. De Villiers also made two tactical changes, starting Gurthro Steenkamp at loosehead prop in favour of Tendai Matawarira and including centre Juan de Jongh on the bench. Fiji made three changes to their run-on side to face the Boks, with coach Sam Domoni saying the Pacific islanders would not be daunted by the reigning world champions. "We respect them but that doesn't mean we limit our expectation of what we're capable of executing on Saturday," he said. "We've seen a few things where we can maximise the team's performance and it should be a very good, exciting game," Domoni named 29-Test hooker Sunia Koto in the starting line-up, also bringing in flanker Akapusi Qera and number eight Masi Matadingo.