BOSTON -- After their bullpen faltered down the stretch, the Red Sox were on the verge of losing their fourth consecutive game for the first time all season. Instead, they took advantage of timely hits and a Marlins error on the final play of the game to secure an 8-7 walk-off victory at Fenway Park on Tuesday night.

With the win, the Red Sox remain the lone team in baseball without a four-game losing streak on their season register as they improved to 91-42. Boston still leads the Yankees, who also won in walk-off fashion, by 6 1/2 games in the American League East.

"It was pretty amazing that we were able to pull out a win tonight," said Jackie Bradley Jr. "Winning's a lot more fun than losing."

After seeing three leads on the night go by the wayside, Boston went into the bottom of the ninth tied at 7 before J.D. Martinez and Xander Bogaerts strung together back-to-back one-out singles. It appeared Eduardo Nunez had grounded into an inning-ending double play, but after shortstop JT Riddle stepped on second base, his throw to first bounced in front of Miguel Rojas and sailed into the camera well along the first-base line to allow Martinez to score the winning run.

"We didn't pitch well in the last-third of the game, but we swung the bats well and we ended up winning," said manager Alex Cora.

Despite having a 4-1 lead heading into the eighth inning, the Boston bullpen got roughed up for five runs in the frame. Matt Barnes allowed four runs and was only able to retire one of the five batters he faced. Richard Hembree didn't fare any better, as he allowed an inherited runner to score and was also charged with a run before Miami finally ended its rally having taken a 6-4 lead.

The Red Sox were not yet ready to go quietly into the night, and they responded promptly.

In the bottom of the eighth, three Boston singles loaded the bases with one out before Miami reliever Tayron Guerrero settled down enough to strike out Blake Swihart.

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Bradley did well to battle the heat being thrown by Guerrero, and on the seventh pitch of Bradley's at-bat, he sliced Guerrero's fastball up the middle for a single to bring home Martinez and Nunez, tying the game at 6.

"Saw a lot of fastballs. A few outside the zone, a few inside," Bradley said. "I took a couple of swings at them, fouled them off and I was able to just compete and put a good swing on a very good pitch."

"Jackie did an outstanding job in that at-bat [by] just being patient and getting his pitch," said Cora.

Ian Kinsler advanced from first to third on Bradley's single, which proved crucial, as he would become the go-ahead run after Guerrero allowed a 98-mph fastball to Mookie Betts to go wild, prompting the Fenway crowd to do the same in the process.

Boston brought in closer Craig Kimbrel to clean things up in the ninth, but that proved a tricky venture after he gave up back-to-back one-out walks, followed by a Magneuris Sierra RBI single that brought things back to even at 7.

"I just didn't execute a pitch that I felt like I should have. Gave up a single through the hole and gave up a run," said Kimbrel, who suffered his fifth blown save of the season but also picked up his fourth win. "We don't want to come out here and give up runs like we did tonight. All we can do is learn from it, take it and go forward from there."

MOMENTS THAT MATTERED

Bradley's eighth-inning at-bat was a test of wills for the Red Sox center fielder. Of the seven pitches thrown by Guerrero, only one was not a four-seam fastball. Five of those fastballs were clocked above 99 mph. After fouling off Guerrero's 100.6-mph heater, Bradley caught up to a 98.6-mph fastball, the slowest of Guerrero's heat that at-bat, to bring home two runs.

"Jackie has swung the bat great the last month and a half, two months," said Cora. "We trust Jackie. We trust his swing and where he's at now offensively. He did a good job fouling off a tough pitch and then going up the middle."

SOUND SMART

With the win, Boston became the 26th team since 1900 and 13th AL team to reach 91 wins within 133 games. It also matches the most wins by the organization before the end of August, tying them with the 1946 team that won 91 before September began.

YOU GOTTA SEE THIS

Derek Dietrich looked as if he had found a nice piece of the left-field turf to drop in a leadoff single in the top of the sixth inning, but Bogaerts had other ideas. With left fielder Andrew Benintendi and Nunez also in pursuit of the popup, a sprinting Bogaerts made a nifty over-the-shoulder catch well into left field to keep the Marlins off base.

HE SAID IT

"I'm not concerned. I think we need to get better. Walks are getting up there now, a lot of 3-1 counts, a lot of two-strike hits. That's not good and they know it. That's something that we've been talking about. We trust the stuff, but at the end, we have to execute. For whatever we are in the standings, we have a lot of margin to improve, which is very important. We don't get caught up on the whole 'We have 91 wins.' We know we have to be better. We know that and we keep working at it." -- Cora, on his bullpen

MITEL REPLAY OF THE DAY

In the bottom of the seventh, Boston challenged the call on the field after Bradley was called out on a steal attempt of second base. After a 41-second review, the call was overturned and Bradley was credited with his 13th stolen base of the season.

UP NEXT

The Red Sox conclude their brief two-game set vs. the Marlins on Wednesday night, with red-hot David Price (14-6, 3.50 ERA) taking the hill for a 6:35 p.m. ET first pitch. In six starts since the All-Star break, the left-hander is 4-0 with a 1.09 ERA, holding opponents to a .195 batting average. Price will look to close his August with his fourth consecutive win. Right-hander Trevor Richards (3-7, 4.23 ERA) will start for Miami.