Handed the ball for what was supposed to be a high-stakes showdown against Max Scherzer, Gerritt Cole gave Houston a firm grip on the Series by beating the Nationals 7-1 Sunday night for a 3-2 lead.

Cole looked exactly like the stud who dominated baseball most of this season, bouncing back from a Game 1 clunker to pitch the Astros to their third straight win.

But then Scherzer was scratched only 3 1/2 hours before game time because of an irritated nerve near his neck, an injury that could finish him for the Series.

Slumping rookie Yordan Álvarez and Carlos Correa each hit an early two-run homer off emergency starter Joe Ross. George Springer added another postseason drive for the Astros, who led the majors with a franchise-best 107 wins during the regular season.

Alvarez hit 27 home runs in 87 games this season, but hadn’t connected in 71 at-bats since Sept. 21.

Cole threw three-hit ball for seven innings, nicked only by Juan Soto’s home run in the seventh, and struck out nine — eight on breaking balls.

The crowd gave Joe Ross a huge ovation when he walked onto the field for warmups, sympathetic to his situation — he had pitched a total of two innings in almost a month.

Cole ended his outing by getting Victor Robles on a called third strike, a pitch the TV zone showed to be off the plate. Robles chucked his bat, helmet and gloves, and the crowd soon began a derisive chant at umpire Lance Barksdale.

Correa made it 4-0 with his homer in the fourth and Yuli Gurriel added a two-out RBI single in the eighth.

Springer’s 15th career postseason home run — seven in the World Series for the 2017 Series MVP — finished off the rout.

With the road team winning every time so far, Houston heads home with two chances to claim its second title in three years. Justin Verlander gets the first try when he starts against Stephen Strasburg in Game 6 on Tuesday night.