Los Angeles: The Chicago Cubs staged an incredible ninth-inning rally to defeat the San Francisco Giants 6-5 and clinch their Major League Baseball play-off series on Tuesday.

The Giants had looked poised to square the best-of-five series at 2-2 after building a 5-2 lead heading into the ninth.

But Chicago’s Ben Zobrist doubled on a line drive to allow Kris Bryant to scamper home for a score to make it 5-3 and leave Anthony Rizzo on third.

A single from Wilson Contreras then allowed Zobrist and Rizzo to score to tie it up at 5-5.

Javier Baez followed with a single on a ground ball that sent Jason Heyward over for the winning run as Chicago completed a remarkable comeback and a 3-1 series win to keep alive their dream of a first World Series crown in 108 years.

“We just got it going and felt something good was going to happen. This win is so huge. We never quit and we aren’t stopping now,” Zobrist said after silencing the AT&T Park crowd.

“For us to do this in this stadium, with these fans, to be able to quiet them and be able to hear the Cub fans, it was nice.”

The Cubs will now face either the Los Angeles Dodgers or the Washington Nationals in the National League Championship Series starting on Saturday.

The Dodgers stayed alive in their series with the Nationals after Chase Utley singled home Andrew Toles with the winning run in the eighth inning to clinch a 6-5 Tuesday win. It set up a decisive fifth game in Washington on Thursday.

After Washington scored three runs in the seventh inning to equalise, the Dodgers plated the deciding run in the eighth after Nationals relief pitcher Blake Treinen hit Toles to put him on first base.

Toles took third on Andre Ethier’s single and scored when the Dodgers’ leadoff man Utley singled to right field.

Los Angeles closing relief pitcher Kenley Jansen retired the Nationals in order in the ninth and the stage was set for a one-game showdown to see which team advances.

The Dodgers used starting pitcher Clayton Kershaw on short rest, gambling on a strong effort with Los Angeles facing elimination, and the move paid off despite early trouble.

Washington took the lead in the first inning, when Trea Turner singled, took second when Bryce Harper walked and scored on a Daniel Murphy single.

Los Angeles took the lead when they came to bat in the first, with Adrian Gonzalez smashing a two-run homer over the right-field wall.

Turner scored again in the third to pull the Nationals level. He singled, took third on a Jayson Werth single and scored on Murphy’s sacrifice fly out.

Kershaw helped his cause in the third with a leadoff double and scored the go-ahead run on a two-out double by Justin Turner.

Nationals pitcher Joe Ross issued two walks to load the bases and then hit Joc Pederson to force in Turner for a 4-2 Dodgers’ lead.

In the fifth, Josh Reddick singled and scored when Pederson followed with a two-out double to left field, boosting the Los Angeles edge to 5-2.

Washington loaded the bases in the seventh inning, prompting the Dodgers to remove Kershaw for reliever Pedro Baez, but he struck Werth with a pitch to force in a run and was removed for Luis Avilan.

Murphy smacked a single to centre field to score two runs and lift the Nationals level at 5-5.