Tweaked on run Weds. 14th - don't know why - just "happened". Seemed to be able to run through it Thurs. & Fri. and felt nothing Sat. a.m. so quite hopeful - but in race just "went" again - no particular reason - just "happened" - what can you do?
Plenty of stretching specific to Hamstring plus invested in Compression Shorts and Tights.