Pistorius qualified first in the men's men's T44 100 metre heats and will compete in the T42/46 4x100m relay final later on Wednesday.
Gautengers Ilse Hayes and Johanna Pretorius, competing in the morning heats, both qualified for the women's 100m T13 final on Thursday and said they would be rooting for Pistorius in the meantime.
"Oscar has been a great support to us," said Pretorius, competing at her first Games. "He is an amazing figure for Paralympic sport and he has boosted the whole idea of the Paralympics. The team are supporting him and he has supported us – it's a two-way thing."
Hayes, who tied second in 12.63 seconds said she was delighted to have qualified after recovering from a torn quadriceps muscle. "I needed the race for my confidence, considering my injury, but it's healing and manageable pain.
"The British crowd are amazing and I'm so happy Johanna has also qualified. We have a really positive spirit in the camp and there are 10 athletes from my training group here, so it is great to share this experience with them."
Pretorius said she was surprised and excited to have made the grade as she too had been struggling with injuries. "I think the adrenaline made me not feel the pain. It's my first ever race at the Paralympics and I don't think it has sunk in yet," the 19-year-old said.
"My dad was there in the crowd and my teammates, who are like family to me."
Qualifying fourth fastest for the men's 100m breaststroke SB5 final was Tadhg Slattery, who suffers from cerebral palsy and is also deaf. Gold medallist in Athens and bronze in Beijing, Slattery qualified in 1:39.55 and was beaten by Niels Grunenberg of Germany (1:36.97) and Mexican Pedro Rangel (1:37.97) in their heat.
Together with Korean Woo-Geun Lim, who swam 1:34.94 in the other heat, the trio would be his main stumbling blocks to a medal.
"The standard this year is very, very high," said Slattery, through an interpreter. "It has been getting tougher and tougher every four years and it's going to be a tough race tonight."
It was unusual for Natalie du Toit to find herself only the seventh fastest qualifier in the women's 50m freestyle heats. She had indicated she would find it tough as it had been some time since she swam the length in under 30 seconds.
Britain's Louise Watkins came close to Du Toit's 29.04 world record, set at the Commonwealth Games in 2006, winning the heats in 29.35.
Kevin Paul was back in the pool after a five-day break, progressing to the finals of the men's 400m freestyle S10 event, finishing third in his heat. He set a new African record in 4:19.64, but only just made the grade as the eighth-fastest qualifier, with the quickest competitor, Ian Silverman of the United States, a good six seconds ahead of him.
Achmat Hasseim, nicknamed "Shark Boy" after he lost his right foot in a shark attack, missed out on the final, clocking 4:27.86.
Bronze medallist from Tuesday night, Shireen Sapiro also just scraped into the final of the women's 400m freestyle S10 event, in 4:59.54.
Like Paul, she set an African record in the process, but was a whole 15 seconds slower than the US's Susan Scott, who looked set for a podium finish.
Two South Africans were in action at Brands Hatch on Wednesday morning. Roxanne Burns finished sixth in the individual C4 time trial, which took place over 16km, in 32:39.24. She was six minutes behind the winner, America's Megan Fisher, who completed the distance in 26:04.39.
Jaco Nel rode the individual C2 time trial in 28:12.44, coming 14th, but will be back on the road again on Thursday in the men's C1-3 road race. – Sapa