* Leaders complete only five holes Sunday * Tournament shortened to 54 holes (Adds quotes) May 1 (Reuters) - World number one Jason Day moved within three strokes of the lead during the third round at the weather-plagued Zurich Classic of New Orleans on Sunday before more torrential rain halted play for the day. Officials shortened the event to 54 holes and extended it to a Monday finish, with the third round scheduled to resume at 7 a.m. local time (1200 GMT). Co-leaders Brian Stuard and Jhonattan Vegas were five holes into their third round when play was suspended after steady rainfall continued to saturate the TPC Louisiana layout. More...