SOUTH Africa's track and field stars produced four medals at the World Championships in Daegu last year.

But how will that convert into silverware at the London Olympics, the biggest stage in athletics?

Here are our medal hopefuls:

1 Sunette Viljoen (women's javelin)

Viljoen won bronze at the World Champs, and so far this year she is performing even better, going into orbit with the best throw in the world to date in 2012.

Viljoen threw an African record of 69.35m in New York last month, making her the early front-runner for the Games.

That throw would have earned her fourth spot in the men's javelin competition at the African Champs in Benin this week.

Viljoen, however, missed the continental competition because of a minor back injury - apparently just a preventative measure.

2 Caster Semenya (women's 800m)

If Semenya can match - or improve on - her 1min 55.45sec personal best from 2009, she will have a great chance of winning gold.

She faces some stiff competition from Kenya's defending Olympic champion Pamela Jelimo (1:54.01 personal best), reigning world champion Mariya Savinova and Ethiopian Fantu Magiso.

Semenya's 800m times this year have been way off the pace, but consider that just last month she clocked an impressive 600m PB of 1:25.56.

She will be a contender in London.

3 LJ van Zyl (400m hurdles and 4x400m relay)

Van Zyl is a phenomenal competitor and a talented athlete. He proved that last year when he broke the 48-second barrier on four occasions, clocking the year's best time of 47.66sec in the process.

But this year he has been off.

Van Zyl first struggled with a niggle in his right knee, and at the recent African Champs he fell ill with a mystery virus. Let's hope Van Zyl can recover.

At the World Champs he won two medals, 400m hurdles bronze and silver for the 4x400m relay.

If Van Zyl is not on form, we stand to lose out on both medals.

4 4x400m relay team

The relay probably depends heavily on the form of Van Zyl, but equally the other members will have to produce good runs.

Oscar Pistorius, Ofentse Mogawane, Willem de Beer and Shaun de Jager will all have to run the race of their lives - with or without Van Zyl.

5 Khotso Mokoena (long jump)

He famously won South Africa's only medal at the 2008 Olympics, a silver medal with a modest distance of 8.24m.

By the end of the year, Mokoena's Olympic jump placed him only 13th on the world rankings. This year he is lying fifth.

6 Marathon (men and women)

South Africa have qualified the full complement of three men and three women for the marathons.

On paper they face a tough task, but that's what we would have said before Josia Thugwane came from obscurity to win gold at the 1996 Games in Atlanta.