WASHINGTON — Mark Vientos’ emergence for this final stretch would be more than a luxury for the Mets.

“He was a key contributor for us last season, and neither he nor we are experiencing the season we expected,” manager Carlos Mendoza noted on Tuesday prior to the Mets’ 8-1 win against the Nationals. “However, we require his contribution now.”

Vientos responded to the challenge by hitting a home run for the second consecutive game. In the third inning, Vientos launched a two-run homer off Jake Irvin, extending the Mets’ lead to 5-0.

Starting as the designated hitter, Vientos energized the team on Sunday with his three-run home run in Williamsport, Pa., which secured a victory over the Mariners.

His playing time had decreased lately, along with his production. Vientos took a .573 OPS for August into the day.

“I am showing up every day like I am starting and going about my business,” Vientos said. “I am just focusing on winning. I just want to win and whenever I get the opportunity help the team in whatever way.”

But the way Vientos has looked in recent days suggests he won’t be sitting much in the near future.

“He’s going to continue to get his opportunities and he’s a big part of this team,” Mendoza said.

Tuesday marked the first game in MLB history that included two managers of Venezuelan descent — Mendoza and the Nationals’ Miguel Cairo.

The ball used for the game’s first pitch was to be removed and sent to the Hall of Fame.

Cairo became the Nationals’ manager after Dave Martinez was fired in July, along with longtime general manager Mike Rizzo.

Cairo was the Yankees’ minor league infield coordinator during Mendoza’s stint with the organization as a major league coach.

“It’s just an honor for both of us — a privilege,” Mendoza said. “I am humbled by it. This is a big deal back home. I am happy to represent our country.”

Mendoza had previously managed a spring training game against a fellow Venezuelan — Astros bench coach Omar Lopez.

Hitting coach Eric Chavez coached third base, with Mike Sarbaugh back at the team hotel due to illness.

Before the Mets can look to next week’s series against the first place Phillies at Citi Field — the NL East foes have seven games remaining against each other — there is the matter of navigating this stretch, facing the underwhelming Nationals and Braves.

“We have got to win some games,” Francisco Lindor said.

The Mets swept the Nationals in June at Citi Field to move a season-high 21 games above .500.