Houston Astros won the longest play-off game in major league history to defeat Atlanta Braves 7-6 and take a decisive 3-1 advantage in the series.
Burke launches the winning hit in the bottom of the 18th inning
Chris Burke smashed a solo homer off relief pitcher Joey Devine to end a marathon encounter, the equivalent of two full regulation games.
The Astros now face Central Division rival St Louis in the National League Championship Series.
It is the second consecutive season that the two teams will have met.
"It was mentally draining," 25-year-old rookie Burke said. "I feel blessed to have got the opportunity and I am just glad I could do my part."
Meanwhile, New York Yankees took their series with Anaheim Angels into a deciding match after winning the fourth game 3-2.
Ruben Sierra delivered a key hit in a two-run seventh inning, and closer Mariano Rivera pitched two perfect frames as New York rallied superbly to clinch victory.
Bartolo Colon will face New York's Mike Mussina in the deciding encounter in Anaheim on Monday.
There will be little respite for the victors, with Chicago awaiting in the American League Championship series opener on Tuesday.