The best way of training for that sort of distance is just to run it - fast! Fartlek training is good because 10k is a 'short' distance to run; you need to be running pretty much full-on from the work go IMHO.
I'd suggest some 1 - 1.5hr runs with sprint intervals in them, then lower the distance but up the speed. For a 10k you want to be finishing the last 1km pretty much flat out.
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