More of a comment than a guide: I got this by fluke really. Playing as Liverpool, Steven Gerrard got injured but there was no in-game mention of it. One of the commentators just said he looks tired and he moved a lot slower than normal but the rest of his skills seemed fine. I scored with Gerrard a few minutes later off a corner kick. This was just an exhibition match.
However, after starting career mode, I noticed that players get small injuries more often (pulled muscles, cramps, etc..) so if you play the career mode without a virtual pro, you should get this fairly easily.