CLEVELAND -- If the Phillies end up missing the postseason -- a possibility that inches closer to reality each day they fail to make up ground in the National League Wild Card race -- the fifth inning of Sunday’s 10-1 loss to the Indians at Progressive Field may prove to be one of the more unpleasant and unsettling frames of the campaign.

It was then, with the momentum seemingly on the verge of shifting to Philadelphia’s dugout, the Phillies squandered an opportunity to break Sunday’s tie. Moments after an inning-ending double play kept the game knotted at one in the top of the frame, a pair of Philadelphia errors eventually led to Oscar Mercado’s back-breaking three-run homer to the bleachers in left field in the bottom half.

The Phillies never recovered.

• Box score

The Mercado bomb off starter Vince Velasquez eventually paved the way for the Sunday night rout, dropping Philadelphia to six games back of the two NL Wild Card leaders -- the Nationals and Brewers -- with only eight games remaining to make up the difference.

“We’ve got our work cut out for us,” manager Gabe Kapler said. “We’re going to have to win out. We understand that that’s a tall task. We also understand that that’s a possibility. There’s not a guy in that room that’s not going to fight until the very end.”

The blowout was even more deflating given that, with the score tied in the fifth, the first two batters for Philadelphia reached base. But after a Scott Kingery double and an Adam Haseley single seemed to have the Tribe teetering, Indians starter Adam Plutko got César Hernández to pop out. Then, Carlos Carrasco entered to coax J.T. Realmuto into a rally-killing double play.

“Those are the type of situations you have to cash in on in big games,” Kapler said. “J.T. banged that ball pretty hard, he just banged it right on the ground. That was the goal right there for the Indians. They wanted to get a ground-ball double play. We weren’t able to come through in that situation. J.T. has been tremendously clutch for us on so many occasions. He put a good swing on that ball, he just hit it on the ground.”

Minutes later, Greg Allen and Roberto Pérez each reached on errors. The first was committed by shortstop Jean Segura. The second came when Velasquez failed to secure a bunt attempt.

“If they’re giving you outs, you’ve got to take advantage of them,” Velasquez said. “In that situation, Perez bunting, I don’t know what he’s doing, but [making the play is] my job.”

In total, the Phillies were charged with three errors on Sunday night.

“In order for us to win big games, we have to take the outs that they give us,” Kapler said. “We didn’t play our best defensive game. I don’t think there’s any way you can spin it like we were anything other than not on top of our game, defensively.”

After two outs offered some hope that the Phillies could pull off an escape of their own, Mercado’s blast sent them staggering. Two innings later, Cleveland's six-run seventh inning provided the knockout punch.

“The first pitch was a curveball, he fouled it to the right,” Velasquez said of his exchange with Mercado. “The second pitch, fastball, he fouled it right back. I tried to challenge him with another fastball. He got the head up.”

The potentially crippling blow to the Phillies’ lingering postseason hopes sets up Philadelphia for a final week full of must-win ballgames. That begins with a five-game set against Washington at Nationals Park beginning Monday night.

“I don’t think there’s any type of pressure,” Velasquez said. “We know that Washington is up ahead of us, but that doesn’t mean we can’t go over there and sweep them five games. We know what’s written out there, we’ve just got to go out there and take it.”

Even if the Phillies earn that five-game sweep of the Nationals, they’ll need help in the final week. The Brewers, Cubs and Mets are all currently ahead of Philadelphia in the NL Wild Card standings, while the D-backs are tied with the Phillies at six games back.

“We’ve got our heads right,” Velasquez said. “I don’t think we’re pressing. We know what we’ve got to do. We’re grown ups here. We know what’s in front of us. We know what we’ve got to do individually and as a team. I don’t think we have any kind of doubts about what can happen.”