McCann has played in five successive games and planned to start all three games of the series in St. Louis. But Friday's three-hour, 56-minute extra-inning contest forced a change in plans.
"That 12-inning game put a wrench into that," McCann said. "Today is probably a good game to take off."
McCann, who last sat out last Sunday at Colorado, will be back in the lineup when the Braves open a short four-game homestand on Monday against Cincinnati. He will likely start all four games.
McCann is 3-for-10 in the series and helped the Braves score 16 runs over the first two contests.
"We've [executed] all facets of the game pretty well," McCann said. "We're getting good pitching and we're swinging the bats."
Atlanta carried a 6-2 record into the final game of the trip on Sunday.