Host nation South Africa were left facing the prospect of an early World Cup exit after slumping to defeat at the hands of a Diego Forlan-inspired Uruguay in Pretoria tonight.

Forlan scored Uruguay's opening two goals, the first a deflected 25-yard effort and the second from the penalty spot late on after an incident which saw home goalkeeper Itumeleng Khune sent off.

Alvaro Pereira than wrapped up a deserved victory for dominant Uruguay in stoppage time as the South Americans moved onto four points in Group A and within touching distance of a place in the last 16.

For South Africa, who barely troubled Fernando Muslera's goal during the match, the defeat means they have just the one point from their two matches and are now in some trouble.

Bafana Bafana's final group game is a potentially tough encounter with 1998 world champions and 2006 runners-up France next Tuesday, while Uruguay meet Mexico.

South Africa coach Carlos Alberto Parreira kept faith with the majority of the side that started their opening game against the Mexicans, with the only switch seeing defender Tsepo Masiella come in for Lucas Thwala.

Uruguay coach Oscar Tabarez, meanwhile, made two changes to the side that started Friday's goalless draw with France in Cape Town.

As expected, Edinson Cavani was brought in to form a three-pronged forward line with Forlan and Luis Suarez, while defender Jorge Fucile was also included, with Mauricio Victoriano and Ignacio Gonzalez the men to make way.

Parreira felt that, having got their opening game out of the way, his side would be much more confident and relaxed for their second outing.

However, they immediately found themselves on the back foot once again as Uruguay started brightly and they had four early shots on goal, although none of them troubled Khune.

Siphiwe Tshabalala, whose thunderous finish gave South Africa the lead against Mexico, briefly tried to mount a fightback with two long-range efforts but neither were on target and in the 25th minute Bafana Bafana found themselves a goal down.

Parreira had singled out Forlan as a player his side needed to keep a close eye on, and it was the Atletico Madrid striker who did the damage.

Never afraid to shoot when within sight of goal, Forlan let fly from 25 yards and saw his effort loop over Khune with the aid of a slight but crucial deflection off home captain Aaron Mokoena, the ball clipping the crossbar en route to going in.

That lead was no more than Uruguay deserved, and they almost doubled their advantage in the 32nd minute when Suarez's rising shot hit the side-netting.

The half-time break probably could not have come quick enough for South Africa, but it was Uruguay who continued to boss the game at the start of the second period.

Cavani put a reasonable chance wide early on before the unmarked Uruguay captain Diego Lugano made a mess of trying to turn a Forlan free-kick goalwards.

Then, from nowhere, South Africa almost snatched an equaliser in the 66th minute when Mphela got in front of Uruguay goalkeeper Muslera to get on the end of Siboniso Gaxa's cross.

However, the big number nine could not direct his glancing header on target.

South Africa's hopes of getting anything out of the game were crushed in the 76th minute when they conceded a penalty and lost goalkeeper Khune to a red card.

Forlan's mis-hit shot found its way through to the wide-open Suarez inside the area and, as he looked to round Khune, his foot was clipped by the South African and the Ajax forward went tumbling.

Khune protested his innocence but there was no swaying referee Massimo Busacca, who pointed to the spot and gave the goalkeeper his marching orders.

After a lengthy delay while South Africa reserve custodian Moeneeb Josephs replaced Steven Pienaar, Forlan ensured the maximum punishment from the spot to spark an early exodus for many disappointed home fans.

Those who left early missed Uruguay's final goal in stoppage time, when Pereira bundled home Suarez's cross from virtually on the line.