BOSTON -- When Jackie Bradley Jr. belted a lead-off double off the Green Monster in the bottom of the 11th inning on Sunday night against the Dodgers, the Red Sox started to taste what could have been one of their sweetest victories of the season.

Perhaps Bradley tasted it too much, and it led to his haste in a rare baserunning mistake that haunted Boston in a 7-4, 12-inning loss in the rubber match of a three-game series between the teams that faced off in last year's World Series.

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After Bradley reached in what was then a tie game, the next batter was Marco Hernandez, and he smacked a grounder to shortstop Corey Seager. The play was right in front of Bradley, yet he ran to third, where he was easily thrown out by Seager.

What exactly happened?

“First of all, I messed up,” Bradley said. “But with that being said, my thought process was he was behind me and jockeying me to make sure I stayed close to the base. With the lefty in Marco being up, I thought they were going to be shifted a little bit more toward the middle.

“Initially, I thought it was the right read. Once I went back and looked at the replay and saw Corey, he shuffled over more towards the hole more than I thought he would ... it was a good play by them. It was a tough play for me to read. Instinctually, I just took off, being aggressive to get to third.”

While the Red Sox eventually loaded the bases with two outs, J.D. Martinez grounded out to short to end the tantalizing rally.

“We made a baserunning mistake late in the game when Marco hit the ground ball,” said Red Sox manager Alex Cora. “Just one of those that, we had our chances, didn’t take advantage of it, and then at the end, they did what they did and scored some runs.”

It was a surprising turn of events because Bradley is one of Boston's best baserunners.

“Trying to make something happen,” Cora said. “Seager was right there. That ball, I think was right in front of him. He took off. He knows that you stay at second, and we’ve got Mookie [Betts] and Raffy [Devers] lined up. So, it’s just a mistake, and he knows it. He’s one of the best baserunners we have. Just took off. Probably as soon as he chopped it, he thought he had a good jump and he was going to be safe at third, and it didn’t happen.”

Before Bradley was thrown out, Cora did have the option of asking Hernandez to drop down a sacrifice bunt, which could put the winning run 90 feet away with one out. Cora’s reasoning for not doing so was sound.

“Runner at second. I like taking three shots, you know?” Cora said. “In the end, it was a 3-1 count. He put a good at-bat. He started ball 1, then took a shot. At 1-1, he was patient enough. 3-1, put a good swing, fouled it off, then hit a ground ball to short [on 3-2]. We like taking three shots there.”

Making the missed opportunity more painful is that the Red Sox basically ran out of pitching after the 11th, and had to go with low-leverage righty Hector Velazquez in the 12th, and that went sour quickly.

After Joc Pederson led off with a walk, it appeared the Red Sox would get an out when Cody Bellinger tapped a grounder to first that Brock Holt should have fielded cleanly and fired to second for the force. But the ball squirted off of Holt’s glove and into foul territory.

This forced Velazquez to race to the bag in case Holt needed help. While Holt initially tagged Bellinger out, Velazquez was called for interference on the basepath. Everybody was safe. And the wheels were officially set in motion for what wound up a three-run inning.

“He ran into the runner,” Cora said. “Brock misses the ball, and the runner has the lane. Hector actually was going toward first base because he’s expecting Brock to catch the ball and throw to second, and he ran into the runner.”

Back-to-back jacks not enough
Down 4-2 heading to the bottom of the eighth, Xander Bogaerts and Martinez sent a surge of excitement through Fenway Park when they hammered back-to-back homers against Pedro Baez to tie it up.

But the Red Sox were unable to take the lead in the ninth when they had two on and one out for the ever-dangerous Devers, who worked Dodgers closer Kenley Jansen for a thrilling nine-pitch at-bat which ended in a lineout to left. Bogaerts, on the one-year anniversary of a walk-off grand slam, came up next and struck out.

“We had our chances,” Cora said. “It just didn’t happen.”

This has become an all-too-familiar lament for the Red Sox -- both at Fenway, where they are 21-24, and against teams who are above .500 (19-28).

The 50-43 Sox are 10 games back in the American League East and 2 1/2 games behind the Athletics for the second AL Wild Card spot. At 62-33, the Dodgers look much like the 108-win wagon the Red Sox were a year ago.

“You never want to lose,” Bradley said. “So any time you lose, you feel a sense of disappointment. We have to get back out there and do it all over again tomorrow and compete and try to win that game.”