The Washington Nationals reached the World Series for the first time by beating the St Louis Cardinals 7-4.
The victory ensured a 4-0 MLB League Championship Series clean sweep and completed a remarkable turnaround.
Nationals manager Dave Martinez had faced the sack in May after a 19-31 start to the season.
His team will play either 2017 champions the Houston Astros or 27-time winners the New York Yankees in the World Series, beginning on 22 October.
The Astros lead the Yankees 2-1 in their best-of-seven-series.
“This is about as good as it gets, but we’re not done yet,” said Nats veteran Ryan Zimmerman.
The Nationals relocated from Canada to the US capital and were renamed in 2005 after operating as the Montreal Expos from 1969.
It is not the first time a Washington-based team has made the World Series. The former Washington Senators last did it in 1933 but were relocated to become the current Minnesota Twins in 1961.