The Chicago Cubs kept alive their defence of the World Series title after a thrilling must-win game in Washington.

The Cubs edged out the Nationals with a 9-8 victory to set up a meeting with Los Angeles in the National League Championship Series.

In a night full of drama, Washington made the Cubs work for the win, starting off the game with a three-run homer thanks to Michael A Taylor.

But the turning point came when Max Scherzer allowed four runs in the fifth, with Addison Russell claiming a two-run double and giving the Cubs the lead.

The Nationals continued to put up a fight, making the game last more than four hours and into the early hours of Friday morning.

Pitcher Wade Davis stood out, putting in his longest appearance in five years, and striking out Ryan Zimmerman in the seventh.

Into the ninth, Davis came to the fore again when Bryce Harper was struck out, finishing the game with a seven-out save and securing the Cubs' victory.

This is now the third time the Nationals have suffered a game five NL Division Series loss, while the Cubs are going into their third consecutive NLCS appearance at the Dodger Stadium on Sunday.