Their World Series appearance also means that all National League (NL) teams have played in at least one World Series. The only American League (AL) team that has yet to play in a World Series is the Seattle Mariners, who were part of the 1977 expansion. Prior to this series, the Astros and Nationals had never played each other in a postseason series, despite Houston playing in the NL from 1962 to 2012 until their move to the AL West in 2013. In fact, the Nationals are the only team the Astros have faced in the World Series that they have never faced in a pre-World Series playoff round, since the Astros have faced the White Sox, Dodgers, and Braves during at least one playoff round prior to the World Series. The Astros and Nationals did not play an interleague game in 2019, and last faced each other during the 2017 regular season. The two teams share a spring training site in West Palm Beach, Florida, and opened the 2019 spring training schedule against each other. This was the second World Series to feature two expansion teams, the first being in between the Kansas City Royals and the New York Mets. The Astros were deemed as heavy favorites to win the title. Washington Nationals The Nationals finished the 2018 season with an 82–80 () win–loss record, and started the 2019 season with a 19–31 () record. Second-year manager Dave Martinez began to receive public pressure to be fired by the Nationals. The team engineered a turnaround and finished the season in second place in the National League East, four games behind the Atlanta Braves, ending the year with a 93–69 () record. The Nationals were one of two teams to qualify for the playoffs as a wild card team from the National League. Martinez had missed three games in September due to a cardiac catheterization procedure to treat angina. The fourth-seeded Nationals defeated the Milwaukee Brewers at home in the National League Wild Card Game, coming behind from a 3–1 deficit in the eighth inning to win 4–3. The Nationals then upset the top-seeded Los Angeles Dodgers, who had won the previous two National League pennants, in the National League Division Series. The Nationals were behind two games to one, and won their second and third elimination games of the postseason to take the best-of-five series. The postseason series win