The game was rescheduled for Tuesday night at Busch Stadium. The teams are tied at two games each in the best-of-seven series.
For the second time in the NLCS, the teams will travel without a day off. They'll play Game 6 at Shea Stadium in New York on Wednesday night, as scheduled.
Tom Glavine (15-7) of the Mets and Jeff Weaver (5-4) of the Cardinals both had been scheduled to start Monday on three days' rest. St. Louis ace Chris Carpenter is slated to start Game 6 on Wednesday against rookie John Maine.
The Mets even the series by winning 12-5 Sunday night.
Last Wednesday's NLCS opener in New York was rained out, pushing back the start of the series and forcing the first four games to be played without a day off.