SARATOGA SPRINGS, N.Y. - Mo Plex, the multiple graded stakes-winning New York-bred, has been retired from racing after suffering an injury during training earlier this week, trainer Jeremiah Englehart said Saturday.  Englehart said Mo Plex had a small fracture of the sesamoid bone in his right hind leg, something that was discovered after a routine gallop over the Oklahoma training track in Saratoga. While the horse could potentially make back it to the races next year, Englehart said, there were no guarantees he would return at the same level, so the decision was to retire him.  Mo Plex, a 3-year-old son of Complexity, had a record of 5-1-2 record from 10 starts with earnings of $790,000.  His biggest victory came in the Grade 3, $500,000 Ohio Derby in June at Thistledown. He also won the Bay Shore this year. At 2, Mo Plex won the Grade 3 Sanford and the Funny Cide Stakes.  After his victory in the Ohio Derby, Mo Plex finished fourth to Sovereignty in the Grade 2 Jim Dandy at Saratoga and seventh to Baeza in the Grade 1 Pennsylvania Derby at Parx Racing.  “He gave us quite a ride,” said Englehart, who trains Mo Plex for the R and H Stable of Rick Higgins and Howard Reed.  :: Want to learn more about handicapping and wagering? Check out DRF's Handicapping 101 and Wagering 101 pages.