Long jumper Khotso Mokoena
Mokoena, South Africa's only medallist at the 2008 Beijing Games, failed to launch in the long jump final of the London showpiece on Saturday.
"Definitely gold for Rio, I'm not going to put myself down," Mokoena said. "I can see the standard for the long jump and I can do better than that. "I'm just disappointed that it didn't come out and I'll just have to live with it.
"The next four years I have to fight for it."
Mokoena struggled with the rythym of his run-up throughout the evening and recorded four fouls out of his six jumps. He could muster a best jump of only 7.93m in the final.
Great Britain's Greg Rutherford won the gold medal with a leap of 8.31m, while Australia's Mitchell Watt finished second with a best of 8.16m. Will Claye of the United States took the bronze medal with his best jump measuring 8.12m.
Mokoena said the distances were unimpressive and far below his high standards. "It's not massive jumps at all. That's why I say I have it in me," he said.
"It's just a matter of going back and fixing a couple of things — making sure my run-up is strong, making sure I get my speed a little bit up and get a little bit stronger."
The 27-year-old felt his below-par performance came down to peaking too late in the season. "I've done massive training from last year after [the World Championships in] Daegu," he said.
"I might be able to peak after the Games and I might be able to start peaking from next year.
"I've worked really hard and I know it is coming.
"I can feel it in the body, it just didn't come [in the final]."
Mokoena saved South Africa's blushes in Beijing, firing when none of the other athletes could, and returning home with a silver medal. This time around the swimmers set the pace in the opening week of the Games, with three medals courtesy of Chad le Clos, who secured gold and silver, and Cameron van der Burgh who scooped gold.
South Africa's rowing team of Sizwe Ndlovu, Matthew Brittain, John Smith and James Thompson won the country's third gold medal in the men's lightweight four final.
"It was beautiful. I think the swimmers did well," Mokoena said. "They got the track and field guys hyped up to get medals before we started.
"It's just unfortunate that we have yet to do so, but we have a few athletes left who can bring the medals home.
"It's much better than 2008. I'm not part of the pack, but 2016 is another one."
While the track and field athletes were disappointing in the opening days at the Olympic Stadium, Mokoena felt they could still step on the podium.
"We still have Sunette Viljoen, we have Caster Semenya and the 4×400 [relay team]," he said.
"There is a good chance of winning three more medals."
Meanwhile, Oscar Pistorius was overcome with emotion after he made Olympic history on Saturday. He became the first amputee athlete to compete on the track at the Olympic Games, finishing second in his first-round heat in the men's 400 metres sprint.
"I was so nervous. Thanks to everyone for showing their support," Pistorius said. "I didn't know whether to cry. I had a mixture of emotions.
"It was the most amazing experience. The crowd was amazing." Pistorius clocked 45.44, just 0.37 seconds off his personal best, to qualify automatically in the first of seven heats for Sunday night's semi-finals. – Sapa