Pistorius, 25, is favourite to retain his T44 400m title for single and double below-the-knee amputee sprinters, being the only man to run under 50sec in the final, which ends the athletics action at the Olympic Stadium.
Simmonds, who shot to fame as a 13-year-old in Beijing when she won the S6 100m and 400m double, is looking to repeat the feat — and cement Britain’s second spot in the medals — after retaining her title in the longer distance.
Elsewhere, the majority of sports yet to complete their programme reached a climax, with gold medal matches in Boccia, five-a-side football, men’s sitting volleyball, table tennis, wheelchair basketball and wheelchair tennis.
Sunday sees the quadrennial festival of disabled sport spill out onto the streets of the British capital, with four marathon races starting and finishing on the Mall outside Queen Elizabeth II’s London residence, Buckingham Palace.
Large crowds are expected as the best wheelchair, amputee, blind and visually-impaired 26.2-mile (42-kilometre) racers go past key landmarks in the city, including the Tower of London and the British parliament.
Sunday’s programme also sees the finals of the seven-a-side football and “murderball” — wheelchair rugby — which has proved one of the most popular spectator sports at the Games.
From 1930 GMT, London will bid an emotional farewell to the Olympics and Paralympics, organisers said, with Coldplay headlining a closing ceremony entitled “Festival of the Flame”.
Artistic director Kim Gavin told reporters on Saturday that it will draw heavily on Britain’s rich history of cultural, musical and seasonal festivals, taking spectators on a journey through the seasons to music and dance.
“We have got fantastic visuals and amazing stunts going on. It’s a celebration and recognition of people coming together… What we have tried to do is bring something that feels very raw,” he said.
“We have taken the flame, being part of and representing the human spirit that brings so much power to these Games, and really focused towards the flame going out. That’s our emotion.”
The hosts of the next Olympic and Paralympic Games, Rio de Janeiro, will have an eight-minute slot in the show, to give spectators — and athletes — an idea of what awaits them in Brazil.
“In eight minutes, we are going to try to be contagiously joyful. It is just a taster of what you will get in four years’ time,” co-artistic director Daniela Thomas told a news conference on Friday.
The segment will involve both non-disabled artists and those with a disability, including a routine involving blind ballet dancers and the Brazilian principals at the Royal Ballet in London, Thiago Soares and Roberta Marquez.
Swimmer Daniel Dias, who has won five golds in London, and four-time Paralympic champion sprinter Adria dos Santos will also feature, she added.
The focus on Saturday, however, was on Pistorius, who came into the Games as the most-famous Paralympian but has so far failed to retain two of the three titles that he won in Beijing four years ago.
The “Blade Runner”, who became the first double-amputee to run at the Olympics last month, said on Twitter that he was looking forward to his “last and favourite event”.
Pistorius on Friday qualified in 48.31sec, easing up in the final straight but still a full two seconds ahead of his nearest rivals in both heats.