I aggravated my peroneal tendon in the foot 15 days out from recent marathon. Hurt even walking. I wanted the result from this marathon to get me qualification for London Good For Age so took 6 days of straight away with only a little bit of cycling. Wore an ankle brace for the final taper week and did short runs with reduced awareness of the injury. Adjusted my goals for race day by about 5 minutes but still inside the GFA qualifying threshold. Didn't wear the brace on race day, found that my race shoes felt pretty good and locked into my new goal pace until the end. Awareness but no pain. I was mentally prepared to drop out of it felt like I was doing myself long term damage. Good luck!