Phosphorus
... that the race horse Phosphorus sprained a leg and was rejected by his jockey shortly before winning the 1837 Derby Stakes, during which he aggravated his injury and did not race again that year?
... that the race horse <b id="mwAnY"><a href="./Phosphorus_(horse)" id="mwAnc" rel="mw:WikiLink" title="Phosphorus (horse)">Phosphorus</a></b> sprained a leg and was rejected by his jockey shortly before winning the 1837 <a href="./Epsom_Derby" id="mwAng" rel="mw:WikiLink" title="Epsom Derby">Derby Stakes</a>, during which he aggravated his injury and did not race again that year?