Scherzer is 3-2 with a 2.04 ERA in six career starts at Busch Stadium, striking out 59 in 39 2/3 innings.
In their first year under manager Buck Showalter, the Mets have opened the season by winning five straight series, matching a franchise record set in 2018.
Miles Mikolas (1-0, 1.76) starts for the Cardinals.
Red Sox right-hander Tanner Houck will miss his turn in the rotation when Boston plays at Toronto. Houck is unvaccinated and not allowed to travel into Canada.
Houck was used in relief Sunday, retiring five straight batters in a 5-2 loss at Tampa Bay.
Nathan Eovaldi (1-0, 3.86 ERA) will start the opener of the four-game set against José Berríos (1-0, 6.35) and the Blue Jays.
Joc Pederson and the San Francisco Giants (11-5) are 7-3 on a four-city road trip that wraps up with one game in Milwaukee — a matchup between 2021 division champions. The teams will play the other two games of the rescheduled series in a Sept. 8 doubleheader.