OAKLAND -- The A’s had plenty of reason to believe their bullpen was finally starting to turn a corner after it consistently slammed the door on the Yankees over their previous three games. But the relief corps took a step back Saturday night in one of the ugliest innings of the year.

A two-run lead built up through seven innings disintegrated in a 10-5 loss to the Giants. Yusmeiro Petit took over for Jake Diekman, who had recorded the first out of the eighth, and surrendered three straight singles that cut the lead to one run. That began a carousel of A’s relievers who were pounded for an eight-run eighth, capped off by former Oakland fan favorite Stephen Vogt’s three-run blast into the Coliseum’s left-field bleachers off Ryan Buchter.

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“We just couldn’t get an out,” A’s manager Bob Melvin said. “It was looking like a pretty good situation for Petit. He’s usually reliable for us. Not that they hit really hard balls off him, but three straight hits, which is a little abnormal for him. Give them credit. They went the other way and didn’t try to do too much. It felt like we didn’t get an out for about an hour.”

The nightmare top of the eighth lasted 33 minutes and seven seconds, with five A’s relievers required to finish an inning that saw 11 batters come to the plate for what was the most runs scored by San Francisco in one inning this season. It was the American League-leading 23rd blown save by the A’s bullpen this season in a loss that dropped the A’s a half-game back of the Rays for the second American League Wild Card.

“We just have to move on. It was pretty extreme,” Melvin said. “They had seven or eight hits in a row, with a walk or two mixed in, which doesn’t happen often. Just move on. We just had one bad inning today.”

Oakland’s lead, which was built by Mark Canha’s (“Tom Ace” for Players’ Weekend) 20th home run of the year in the second and some rare small ball in a two-run seventh that saw the A’s register just their fifth sacrifice bunt of 2019, was blown without Liam Hendriks ever taking the mound.

The A’s closer was warming up alongside left-hander A.J. Puk with one out in the eighth. With Giants lefty Brandon Belt set to bat with runners at the corners, A’s manager Bob Melvin elected to go with the left-on-left matchup, but the Giants then pulled Belt for righty Austin Slater. A wild pitch from Puk allowed the game-tying run to score, and Hendriks sat back down in favor of Lou Trivino.

Hendriks recorded a five-out save against the Yankees on Wednesday, finishing off back-to-back days pitched. Had there been two outs in the inning, Melvin said he would have gone to the right-hander, but asking him for another five-out performance was too much.

“If we got one more out, I was going to use him for four,” Melvin said. “Five was just, I wasn’t comfortable with that. Especially after the game was tied. It just didn’t make sense to bring him in.”

Lost in the late meltdown was another strong outing by Chris Bassitt, who limited the Giants to two runs on four hits over 5 2/3 innings.

Bassitt has always carried a power fastball in his arsenal, but he was throwing even harder than usual on Saturday night with a heater that reached upwards of 97.1 mph.

“Chris pitched well again,” Melvin said. “He’s had some good fastballs, but the velocity today might have been the best we’ve seen all year.”

Since the All-Star break, Bassitt has posted a 2.45 ERA in eight starts. A lot of that success has had to do with improved command, which he displayed Saturday with no walks and five strikeouts.

As for the increase in velocity, Bassitt attributed it to the adrenaline felt from the season-high announced crowd of 53,367 fans in attendance for the Battle of the Bay.

“I was amped up for the game,” Bassitt said. “Big crowd and big rival, so I was a little more amped up than normal.”