Slovenia sneak past Algeria
Both coaches said afterwards that their sides had struggled to adapt to the new high bouncing World Cup ball and the semi-synthetic pitch in Polokwane, and that that might have been a factor in Chaouchi's blunder.
Time and again throughout the game, players overhit their passes or failed to tame the ball as it sprang off the surface.
A largely lacklustre encounter took a twist in the 73rd minute when Abdelkader Ghezzal was sent off for handball having already been booked within seconds of coming on.The attacking midfielder was only on the pitch for 15 minutes.
Six minutes later Chaouchi fumbled Robert Koren's harmless looking shot, allowing the ball to squirt through his arms into the bottom left hand corner of his net.
Asked about the playing surface, Koren said: "The turf itself is very fast and it resulted in some mistakes."
Slovenia's only previous appearance at a World Cup finals, in 2002, ended in three defeats but Sunday's win has put them top of the group with three points, two ahead of England and the United States, who drew 1-1 in Rustenburg on Saturday.
"It's going to be more difficult for us now," said Algeria coach Rabah Saadane. "Our great opportunity was today against Slovenia and we missed that opportunity."
Until the goal, the Algerians had been marginally the better side with the bleach-blonde Hassan Yebda bossing their midfield.
But they created few chances with their best opening coming as early as the third minute through a Nadir Belhadj free kick which Samir Handanovic tipped over the bar.
At the other end, Slovenia created little of note until just before the break when a rasping left foot strike from midfielder Valter Birsa forced an acrobatic save from Chaouchi.
Saadane defended Chaouchi and Ghezzal when asked about the mistakes that had cost his team a share of the points.
"Football is full of mistakes and I don't want to blame the two players. I think it was perhaps the state of the turf. Both the ball and the turf were difficult for both goalies."
"The speed and the impact, especially on crosses, was very difficult. The players had to place the balls very carefully."
Asked if he would drop Chaouchi for the next match against the United States on Friday, Saadane replied: "He is the best goalkeeper we have at the moment. It's out of the question."
"He said sorry. He said sorry to the team. But that's only normal and I don't want to go back over the incident."
Slovenia coach Matjaz Kek was also critical of the pitch, which is a mixture of grass and synthetic fibre. This was the first World Cup match ever to be played on it.
"I don't agree with this turf," Kek said. "We only got adjusted to it yesterday with 60 minutes of training. I'm not saying this as an excuse because it was the same for us and Algeria. But there are lots of artificial bits and that means it's a different game."
England's draw with the U.S. in the group's opening match also contained a goalkeeping error, with England's Robert Green producing a howler to gift the Americans their equaliser.
That match was played on grass.