The 109th US Open Championship was heading for a first Monday finish since 1983 after more heavy rain fell on the Bethpage Black course overnight.
The downpour, which began at around 7:10pm on Saturday, quickly saw the greens flood after a week-long barrage of rainfall on Long Island.
That led tournament officials from the United States Golf Association to suspend play for the day with some players in the remaining 60-man field, including halfway leader Ricky Barnes, still not having started their third rounds.
With the storms continuing through the night, and a further three-quarters of an inch of rain landing on the Black course at Bethpage State Park, officials decided to delay play until noon (1700BST), pushing likely fourth round play back into Monday for the first time in 26 years.
Play-offs, the US Open rules call for an extra 18 holes, at the end of the regulation four rounds are not so unusual with Tiger Woods returning to Torrey Pines on a Monday 12 months ago to secure his third championship title with a victory over Rocco Mediate that went to a 19th, sudden-death hole.
USGA officials insisted earlier in the week, after play was all but washed out on Thursday, that they would not name a champion until at least all 72 holes of play were completed.
Barnes leads by one stroke at eight under par from fellow American Lucas Glover, his 132 from two rounds going into the record books as the lowest 36 hole score in US Open history.
Peter Hanson is the leading European Tour member on three under, while English duo Ross Fisher and Lee Westwood are a shot further back on two under.