Olympics-Athletics-Rudisha says tactics are key to 800m defence

* Kenyan switched plans after rival 'took off like bullet' * First man since 1964 to retain Olympic title at 800m * Drug cheats to face full force of new Kenyan law By Mark Trevelyan RIO DE JANEIRO, Aug 17 (Reuters) - Fresh from becoming the first man since 1964 to retain his Olympic 800 metres title, Kenya's David Rudisha has a ready answer when asked why that feat took 52 years. "The 800 actually is one of the most tactical races," Rudisha told Reuters in an interview, two days after producing a decisive kick in the last 300 metres to win his second consecutive gold and match the achievement of New Zealander Peter Snell. "You have to be swift, you have to be very fast in making your decision. Any simple mistake you make, it can be hard for you to correct it during the race. "Like when (Kenya's Alfred) Kipketer, in the final, decided to take off like a bullet in the first 200. I tried to keep up with him, but when I saw the clock, I was also watching at my split, and I saw the clock was about 23-something... I saw it was too fast. "Then I had to hold back a little bit. And then try to gain my rhythm and then try to think of a different tactic, because my tactic going in there was to run from the front. So I had to change the tactic immediately and think of a different strategy." Examples are not hard to find of athletics greats who missed out on the 800m by getting their tactics wrong. After losing to British rival Steve Ovett in the final in Moscow in 1980, Sebastian Coe lamented: "I chose this day of all days to run the worst race of my life. I cannot explain why. I must have compounded more cardinal sins of middle-distance running in one-and-a-half minutes than I've done in a lifetime." Rudisha, who came good despite struggling with injuries since his first gold in London four years ago, said he would now look forward to next year's world championships. But the 27-year-old is not making any predictions about a possible triple in Tokyo in four years' time. "It's quite tough to maintain your form for the next four years. You know that final two days ago, when I looked around I think I was the only finalist from London 2012 who was still here," he said. Rudisha, nicknamed 'King David' in Kenya, said he was happy the East African country had succeeded in rushing through an anti-doping law to satisfy the World Anti-Doping Agency (WADA), without which its participation in Rio would have been in jeopardy. "It has been a bit of a hassle and a bit of a big issue in Kenya," he said. "But now we are happy because everything is in place and whoever is involved, whoever is caught with this issue with doping is going to face the full force of the law." (Editing by Ed Osmond)