Jack Flaherty (2-0) allowed one run on three hits with six strikeouts in five innings as St. Louis snapped a three-game losing streak.
''There was some long innings on my part, just my fastball command hasn't been what it needs to be.'' Flaherty said. ''Tonight was about the offense and what they were able to do from the beginning.''
Strasburg (0-1) was racked for eight runs - seven earned - on eight hits and five walks, two of them intentional. The 2019 World Series MVP was pulled after allowing all three batters he faced in the fifth to reach base, leading to a nine-run inning by the Cardinals.
''His mechanics were a little off,'' Nationals manager Dave Martinez said. ''For us, it's part of the process. He hasn't pitched for a year. We've got to get him out there. We have to stretch him out. We have to build him up.''
Goldschmidt hit his first home run of the season, connecting in the first for his 250th career home run. The longtime Arizona star became the ninth player to hit his 250th career home run as a member of the Cardinals.
Arenado hit his third career homer off Strasburg, a two-run drive in third.
Carpenter also had a two-run drive during the inning, a shot off the right-field foul pole. It was his first hit out of the infield this season after starting 1 for 15 with an infield single.
''I was like doing my inner Carlton Fisk trying to keep that ball fair as best I could,'' Carpenter said. ''It was a good feeling seeing it hit that pole.''
The Cardinals sent 14 batters to the plate and added nine runs in the fifth off Strasburg and Luis Avilan without an extra-base hit.
''I think it was just, 'Hey, let's keep adding on,' and all of a sudden we had a bunch of guys on in a row,'' Goldschmidt said. ''Just a good job really of quality at-bats. It's probably pretty rare you'll have all those singles, walks, sac flies, or whatever.''
Washington infielder Hernan Perez pitched a perfect bottom of the eighth inning, striking out two. This was his eighth career pitching appearance.
''The game, the way it turned out, guys are upset about that,'' Nationals catcher Alex Avila said. ''With him (Perez) going out there and actually being able to go through there it saves an inning for the `pen which doesn't really seem like much now but it can be later on in the week.''
Recording artist Nelly was shown in the crowd on the Busch Stadium video board. Nelly played baseball at University City High School in the St. Louis area before embarking on his rap career.
Cardinals manager Mike Shildt managed his 300th career Major League game since replacing Mike Matheny on July 15, 2018.
Nationals: LHP Jon Lester (COVID-19 list) will throw 45-50 pitches in a simulated game at the team's alternate training site on Thursday.
Cardinals: LHP Kwang Hyun Kim (back) is scheduled to be activated from the Injured List to start on Saturday at Philadelphia. St. Louis shuffled its roster by optioning RHP Johan Oviedo to the club's alternate training site after he tossed 4 2/3 innings in relief of Daniel Ponce de Leon on Sunday.
Washington will send RHP Joe Ross (0-0, 0.00 ERA) to the mound to face St. Louis veteran RHP Adam Wainwright (0-1, 8.22) in the final game of the teams' three-game series Wednesday.
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