Yasmany Tomas, right, hit a three-run home run during the Nationals’ loss to the Diamondbacks. (Toni L. Sandys/The Washington Post)

Reminders of the Washington Nationals’ third division title in five seasons, clinched late Saturday night, were spotted around Nationals Park on Monday. New nameplates with 2016 NL East Champions logos were mounted above each locker in the home clubhouse. The video boards in the outfield featured a division title graphic as the team warmed up to face the Arizona Diamondbacks. The Nationals were back home to finish the regular season certain they will return to the playoffs and play Game 1 of the National League Division Series against the Los Angeles Dodgers on Oct. 7.

Yet there would still be plenty on the line over their final seven games. Washington entered the night with a 11/2-game lead on the Dodgers for home-field advantage in the best-of-five NLDS. The Nationals ended it with a 14-4 loss, the gap on the Dodgers down to one game, and another injury to a player important to their World Series hopes hanging over them.

Already without ace Stephen Strasburg (elbow), MVP candidate Daniel Murphy (buttocks) and reigning MVP Bryce Harper (thumb) for injuries varying in severity for undetermined periods of time, the Nationals saw catcher Wilson Ramos, another all-star, exit Monday’s defeat during the sixth inning with a right knee injury. Max Scherzer, Tuesday’s starter, is the only one of Washington’s five all-stars not dealing with an injury.

“There’s nothing you can do about it,” Nationals Manager Dusty Baker said. “You got to play. You got to play and nobody feels sorry for you, so we’re not going to feel sorry for ourselves.”

Ramos injured the knee after he jumped for a sailing relay throw home from first baseman Ryan Zimmerman and landed awkwardly on his right leg without any contact shortly after the game resumed following a 20-minute rain delay. He immediately crumpled to the ground in pain and pointed to his knee, the same one that required two surgeries to mend a torn anterior cruciate ligament and medial collateral ligament in 2012. Nationals trainer Paul Lessard tended to the 29-year-old catcher. He walked off slowly with assistance on each side, not putting any weight on his right leg, and was carried into the dugout as distraught teammates looked on.

Baker said Ramos “doesn’t look too good tonight” and is scheduled to undergo an MRI exam Tuesday morning to determine the extent of the injury. In the meantime, the Nationals will turn to rookie Pedro Severino, who replaced Ramos on Monday, and Jose Lobaton for catching duties.

“Worry does no good,” Baker said. “I feel badly because you know how we all feel about Wilson, but it’s part of the game. You hate [for] it to happen this late, right before the playoffs, but our next step is try to figure out a way to play without Wilson.”

A significant injury at this juncture would be a cruel twist for Ramos. The catcher was kidnapped in his native Venezuela in 2011 before injuries riddled his first five full years in the majors, and he dedicated this season to his grandfather, who died in late April. He has avoided significant injuries and, with the help of improved vision following eye surgery in spring training, has posted his best campaign on the brink of free agency.

A first-time all-star in July, Ramos jumped out to a torrid start and was baseball’s best offensive catcher until the second week of August, when he slipped into a slump. He had reversed the nosedive over the past couple weeks and has set career highs in home runs, RBI and hits. Entering Monday, he had a .307 batting average and .851 on-base-plus-slugging percentage. Both are also career bests. The production boosted Ramos’s stock enough for him to decline a three-year contract extension worth just over $30 million the Nationals recently offered in anticipation of a bigger payday this offseason.

“He’s been unbelievable, the year that he’s had,” infielder Stephen Drew said.

Ramos exited Monday’s game 1 for 3 with a run scored and the Diamondbacks leading 7-4 after pounding Nationals right-hander Tanner Roark.

Roark, so reliable to pitch deep into games all season, lasted just four innings. After Roark tossed three perfect frames, the Diamondbacks, buoyed by Yasmany Tomas’s three-run home run, pounced for five runs in the fourth inning. Roark was due to hit with the bases loaded and one out in the bottom of the inning, but Baker chose to replace him with pinch hitter Chris Heisey.

The decision initially backfired — Diamondbacks right-hander Archie Bradley struck Heisey out looking — but Brian Goodwin worked a walk after falling behind 0-2 to plate a run and Trea Turner followed with a two-run double — one of his three hits — to cut Arizona’s lead to 5-4.

Bradley then walked Jayson Werth to load the bases, but the Nationals wouldn’t score again. Randall Delgado struck Anthony Rendon out to escape the jam and begin the Arizona bullpen’s four-man scoreless effort over the final 5⅓ innings.

Washington’s bullpen was not as stingy. Yusmeiro Petit, who relieved Roark in the fifth inning, surrendered five runs, four earned, across 1⅓ innings and Lucas Giolito allowed four more, including back-to-back home runs, over the final two frames.

But all attention was on the man not squatting behind the plate during the rout. Baker tried to massage Ramos’s injury with some positive news, revealing that the X-rays on Harper’s left thumb came back negative and the right fielder is expected to return later in the week. But less than two weeks before the start of the playoffs, stunned anguish filled the clubhouse.

“It sucks,” Roark said.