BOSTON — Sunday doesn’t merely carry the possibility of a disappointing and sudden end to a breakout regular season for the Red Sox.

If Boston, which won the AL East title this year after consecutive last-place finishes, doesn’t extend its American League Division Series against the Indians, it will be the end of David Ortiz’s 20-year career.

The Indians, who won the first two games of the best-of-five series, will send Josh Tomlin to the mound against Clay Buchholz, weather permitting.

Ortiz, who announced his intent to retire before the season and is off to a 1-for-8 start in the series, did not stop to talk to reporters in the clubhouse after batting practice Saturday. But on the field just before taking batting practice, the 40-year-old DH made it clear that the possibility of his career ending Sunday was very much on his mind.

“We’re not done. We haven’t got in a rhythm yet. I think we will,” he told The Boston Globe. “I want to keep playing. I’m retiring, but I want more games.”

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Buchholz, who struggled much of the year but posted a 3.14 ERA in his final five starts, said winning a World Series for Ortiz has been a motivating force since February.

“Everybody had it mapped out in their head in spring training what we wanted to do, knowing that David was not going to be here next year,” Buchholz said. We reached the first goal and that was to get in the playoffs and win the division. The second part of it has not worked out the first two games.”

Added AL MVP candidate Mookie Betts: “We obviously want to win the ring to send him off. That’s just another motive for us to get back and get going tomorrow.”

The Red Sox, who led the majors in runs this season with 878, were outscored 11-4 in the first two games in Cleveland. They hope a team meeting held before Saturday afternoon’s workout will help them play the way they did much of the season in going 93-69. The Red Sox were 47-34 at Fenway, where they outscored the opposition 477-380.

“We love playing here in front of the fans,” said Brock Holt, one of the few Red Sox to perform well at the plate in the first two games (4-for-8 with a homer). “Cleveland showed us what home-field advantage can do, so we’re hoping to have that here.”

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And the primary message discussed in the meeting, called by the players but attended by players and staff?

“Just be confident in ourselves,” Betts said. “We’re a really good team and just to believe that and play like it.”

The Indians, managed by former Red Sox manager Terry Francona, have no interest in allowing Boston off the mat and would very much like to send Ortiz on his way.

“We have a long ways to go,” said Indians reliever Andrew Miller, a star for Cleveland since being acquired by the Yankees on July 31. “We held court at home. These games, especially in a five-game series, momentum changes so quickly. We certainly can’t let our foot off the gas. We’re certainly not celebrating anything at this point. We have a lot of work to do.”

Francona, who led the Red Sox to World Series titles in 2004 and 2007, said his young club needs to be prepared for the uniqueness of Fenway, which he called “a pretty special place.”

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“Because of the fan base, the way they’re so enthusiastic and rabid when they start to get something going late, this place starts shaking and you can feel it,” he said. “You need to be prepared for it because you know it’s going to get crazy.”