Novak Djokovic reached the Miami semi-finals on Wednesday by beating Kevin Anderson, extending his winning streak and avenging a loss two years ago to the South African in the same city. World number two Djokovic defeated unseeded Anderson 6-4, 6-2 in a quarter-final match at the USD 9 million ATP Masters 1000 hardcourt tournament."When I was two breaks up in the second set I was comfortable sure, but not before that," Djokovic said. "In the second set I found that momentum, but I went through situations where I faced a couple of break points in the first and second set, and I saved them."I was fortunate in those moments." Djokovic, who has won all of his 22 matches this season, will face American Mardy Fish in the semi-finals.Djokovic has now won 24 consecutive matches dating back to last year's Davis Cup final."You obviously get confidence with 24 wins in a row," he said. "It keeps getting better. But I don't want to be carried away with that."I want to keep on working hard and taking one match at a time. When it stops, it stops."The Serb is looking for back-to-back titles in Indian Wells and Miami. It would be his fourth title this season to go with victories in Dubai, Indian Wells and the Australian Open.Anderson became South Africa's first ATP winner in more than five years when he took the title in Johannesburg in February.Anderson won their only prior meeting by beating Djokovic in three sets in the second round in Miami three years ago.At the time, Djokovic was ranked third in the world and Anderson was ranked 122nd.Djokovic will be the heavy favourite against 14th seeded Fish who will pass Andy Roddick as the No. 1 ranked American player when the next ATP Tour rankings come out.Fish has had an up and down year, making two semis in Delray Beach and Memphis but losing in the second round of both the Aussie Open and Indian Wells.He lost twice this year to 20-year-old Milos Raonic of Canada in the second round at Indian Wells and the semis in Memphis.