CAPE TOWN, Sept 9 (Reuters) - A hat-trick inside the opening 20 minutes from captain Chris Katongo steered Zambia to a 3-1 win over South Africa on Sunday and a place at next year's African Nations Cup finals. Zambia snatched top place in Group 11 from their hosts on a better head-to-head record, leaving South Africa to await the outcome of the other qualifiers before being assured a berth as one of the best runners-up at the tournament in Ghana. Katongo took advantage of defensive lapses to stun the crowd at Cape Town's Newlands stadium. He intercepted a poor square ball across the South African back four to open the scoring in the ninth minute. Another errant pass 10 minutes later allowed Isaac Chansa to race away with the ball and square for Katongo to apply a finishing touch. He completed his hat-trick 10 minutes later, heading home a cross from Jacob Mulenga. South Africa pulled a goal back five minutes into the second half through Blackburn Rovers striker Benni McCarthy, making his return the side for the first time in 18 months. It was a record-equalling 29th goal for his country for McCarthy, who headed home a cross from Surprise Moriri. Delron Buckley hit the post 60 seconds later but South Africa were unable to create any more real chances.