BOSTON -- It was just a little bloop into left, really. But the way things had been going for the Red Sox this weekend against the defending World Series champion Astros, it looked as majestic as a towering home run.

With two outs in the bottom of the ninth, Mitch Moreland dunked a walk-off flare, and it sliced out of the reach of left fielder Marwin Gonzalez, who also mishandled it on the bounce. Tzu-Wei Lin raced around from second, and the Red Sox had themselves a hard-fought, 6-5 victory to salvage the final game of a riveting three-game series between two of the top teams in the game.

For Moreland, who started the game on the bench, it was a nice reward amid a recent stretch in which a slump was compounded by his misfortune of hitting the ball right at people.

"Yeah, I mean I'll take those every time," said Moreland. "If I could, I would. Right time to do it, I guess. Hard-fought game both ways. Had a little mishap there. They scored four that one inning and tied it up. To create some opportunities and stay in the game, to get the win was nice."

The win put Boston's magic number at one for clinching a postseason berth and 11 for winning the American League East. The Red Sox improved their MLB-best record to 98-46.

"That was awesome," said righty Rick Porcello, who took a no-decision. "Good ballclub over there, especially avoiding the sweep, especially the way we did it. It's a good win for us; we needed it."

Andrew Benintendi started the winning rally when he belted a one-out single to left. He was out at second on J.D. Martinez's grounder. Xander Bogaerts capped a 4-for-4 night with a single to center. That set up Moreland, who got enough of a 2-1 offering from Hector Rondon to bring home the seventh walk-off win of the season for the Red Sox.

The victory took the sting away from the bullpen squandering a good effort by a starting pitcher -- this time Porcello -- for the second time in three nights.

"I mean, [the win was big], especially with the way the game was going and that sixth inning happened," said Red Sox manager Alex Cora. "That's not fun. Then we had the bases loaded and we don't score. Craig [Kimbrel] did an outstanding job to get us a chance to win the game. It's always good to win. We know what happened today throughout the league. Just another day and we won. Tomorrow is an off-day, so in two days, we get to the next series."

The Red Sox got a big swing from Martinez in the bottom of the fifth, a three-run homer over the Green Monster that gave them a 5-2 lead. It was No. 40 on the season for Martinez, who moved within one of Oakland's Khris Davis for the MLB lead in homers.

"It was good to avoid the sweep," said Martinez. "They battled back. They got in the game. We battled back. I think today what you saw on display was two really good offenses, two really good pitching [staffs], two really good teams. It definitely felt like a playoff atmosphere. You know when you're playing a good team. You can just see the matchups. Every matchup is tough. I don't think there's any break in the lineup. You don't feel like there's any break from the pitchers coming in. It's just tough."

However, Martinez's shot didn't give the Red Sox the momentum they expected. The Astros came storming back in the top of the sixth. Jose Altuve started the climb back when he ripped a solo shot to left against Porcello. Yuli Gurriel and Carlos Correa came up with back-to-back one-out singles, but Porcello did induce the second out on a liner to right by Gonzalez.

With Porcello at 95 pitches, Cora came out to get him. That move backfired. Tyler White greeted reliever Richard Hembree with a two-run double to left to make it a one-run game. Lefty Christopher Johnson was called on next and he walked Brian McCann and then gave up a game-tying double to Josh Reddick.

"I'm not going to object to any of those guys coming into the game," said Porcello. "I think our starters are throwing the ball well this year. But our bullpen has been equally important and carried us up to this point. Heath Hembree, I'll turn the ball over to him every day of the week."

The Red Sox didn't get deflated. Instead, they stayed in it, thanks to two scoreless innings from Steven Wright and then a shutdown ninth by Kimbrel.

And they stole back the momentum for good in the ninth, setting off the latest walk-off celebration at Fenway.

"We need every one of them. We're trying to win every one of them. You don't want to lose any of them. It's going to happen but we take pride in going out and trying to win and that's the way we feel about all of them," said Moreland.

MOMENTS THAT MATTERED

For the Red Sox, one of the keys to the win came in the top of the seventh. After a passed ball by catcher Sandy Leon, the Astros had Altuve on third with one out. With the infield playing in, Gurriel hit a grounder to short and Bogaerts fired to the plate, but the throw was high. Leon made a nice swipe tag, and Atuve was called out. The Astros called for a challenge, as it looked like Altuve might have gotten his hand on the plate before being tagged. After a review of three minutes and 50 seconds, the call stood, and the Red Sox got a big out.

"All the angles that we had were inconclusive so we got that one," said Cora. "When I went down there, I looked at it and I was like, that's one of those that might go the other way. The longer it took was one of those that the angles were tough and we got the call."

SOUND SMART

This is the sixth time in franchise history the Red Sox have reached 98 wins in a season and first since 2004, the magical year when Boston snapped an 86-year championship drought.

HE SAID IT

"He's been calling himself Luis Castillo lately, a lot of singles." -- Cora, on Martinez ending his homer drought at 28 at-bats

MITEL REPLAY OF THE DAY

In the bottom of the fifth, Benintendi hit one deep into the second-base hole and Altuve ranged over to make a terrific stop. Altuve had to rush his throw and bounced it to first, and Benintendi was originally ruled out. But the Red Sox challenged the play and it was overturned, which proved fortunate when Martinez stepped up next and belted his three-run shot.

UP NEXT

Ace Chris Sale (12-4, 1.97 ERA) will return from the disabled list Tuesday and serve as the "opener" in the first of a three-game series against the Blue Jays. Sale is expected to throw two innings and a maximum of 40 pitches. He was sidelined with mild inflammation in his left shoulder and last pitched for the Red Sox on Aug. 12. Toronto counters with lefty Ryan Borucki (3-4, 4.39 ERA). First pitch is scheduled for 7:10 p.m. ET.