South Africa have booked their place in the World Cup semi finals narrowly avoiding upset with a very scrappy 37-20 win over Fiji in Marseille.

Fiji, only trailing 13-3 at the interval, looked to be out of the game when JP Pietersen scored to put the Springboks 20-6 ahead and Seru Rabeni was sent to the sin bin for a high tackle.

But the Pacific Islanders showed incredible spirit to bounce back with two tries in two minutes, still with only 14 men on the pitch, and set up a tense finale before South Africa got back on track with Juan Smith and Butch James touching down to secure victory.

South Africa started confidently with Smith collecting the high ball and charging towards the try line winning an early penalty when Fiji were caught coming in from the side on the ruck.

But Percy Montgomery, whose kicking was decidedly sporadic throughout the match, bounced the ball of the outside of the right posts letting Fiji off the hook.

There was no such mistake from Francois Steyn five minutes later though when Fiji were penalised for illegally turning over the ball and the 20-year-old thumped the ball low between the posts from over 50 metres out to give South Africa a three point lead.

After a shaky start from Fiji they began to get themselves into the match charging down an attempted Steyn clearance before Montgomery managed clear the lines. But it was a signal of intent from the Fijians as they stepped up their physical challenge.

But South Africa, the favourites to lift the Webb Ellis Trophy now that the All Blacks have departed the tournament, extended their lead with a well worked try: Montgomery made the break before Fiji were penalised for dragging down the maul. South Africa opted to push for the try rather than take the three points and they spread the ball to Jaque Fourie who charged unchallenged over the line.

Fiji were the next to put points on the board after a period of spirited play from both sides, when Bakkies Botha was penalised for bringing down the maul and Seremaia Bai calmly put the ball between the posts.

South Africa, however, were determined to begin the half on the front foot and ensured they would do so using the rolling maul to great effect with skipper John Smit, at the bottom of the pile, being awarded the second try of the game.

Again Montgomery failed to add the conversion to the scoreboard leaving South Africa with a fragile 13-3 lead heading into the second half.

Fiji, taking confidence from their outstanding World Cup performances, came out strongly in the second half and within four minutes Bai had cut the deficit to just the seven points with another sweetly struck penalty kick.

But despite the best efforts of Mosese Rauluni and Rabeni, the Springbok defence stood firm before Steyn and lightning-fast winger Bryan Habana broke on the counter attack.

But it was Pietersen who would get the South Africans back into the match receiving the ball on the right wing and skipping round his tackle to touch down unchallenged just to the left of the posts.

The Fijians looked well and truly out of the match when, already trailing by 12 points, Montgomery added conversion and Rabeni was send to the sin bin for a high tackle on a dummy runner earlier in the move.

But South Africa had not counted on the stubborn Fijians and switched off allowing Vilimoni Delasau a change to chip the ball over the heads of Montgomery and Fourie and chase through, getting lucky with the bounce, to touch down just inside the dead ball line.

Bai added the conversion before Fiji incredibly added a second breaking from within their own half and passing the ball through the hands of Rauluni and Norman Ligairi before finding Sireli Bobo who took the ball over the line. Bai again added the conversion to level the match at 20 points apiece.

Montgomery steadied a decidedly shaky South African team four minutes later with a penalty after Fiji were caught coming in from the side while Rabeni re-joined the action setting up a tense finale to the match.

Fiji capped another very successful 10 minutes when Ifereimi Rawaqa received the ball on the left wing and forced his way over the line but a last ditch tackle from Pietersen forced the powerful second rower into touch preventing him from touching down.

Just two minutes later South Africa had recovered enough composure to put them very much back in the driving seat when Smith saw his opportunity from the back of a driving maul to dive over the line and, with Montgomery's conversion, the Springboks re-established a 10 point lead.

There was still time left for Fiji but South Africa killed the game making sure they kept the ball inside the Fiji 22 before James capped the win with a try after Schalk Burger had spilled two attempts.

Montgomery added the extra three points with the final kick of the game to set up a semi final with either Argentina or Scotland at the Stade de France next Sunday.

Pippa Davis / Eurosport