OAKLAND -- Blake Treinen's first day off the injured list did not go exactly as planned.

A’s manager Bob Melvin was hoping to find a low-leverage situation for the right-hander to make his first appearance back from a strained right shoulder, but baseball has no guarantees. Holding off as long as he could, Melvin reached a point where it was necessary to use the closer in the 12th inning, and Treinen faltered, giving up the go-ahead run as the A’s fell to the Twins, 4-3, at Oakland Coliseum.

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“I told him, ‘If we get into a 12-inning game, I might have to use you.’ That’s exactly where we were,” Melvin said. “It wasn’t ideal, but unfortunately, it came to that.”

After striking out Jonathan Schoop to begin the 12th, Treinen issued back-to-back walks before giving up the go-ahead RBI single to Mitch Garver. This season, walks have been a problem for Treinen, who has issued 12 over his last 16 appearances.

Typically sitting around 97-99 mph, Treinen’s velocity dipped as low as 92 in the at-bat against Garver, but Melvin said that was likely a product of trying to slow things down in an effort to throw more strikes and avoid a third consecutive walk.

“He was trying to throw a strike,” Melvin said. “Maybe take another outing and try to get him a different look for an inning and hopefully, [the velocity] comes back.”

The way things went early, Melvin’s original plan for Treinen was looking like it might come to fruition. The A’s jumped out front on Ramon Laureano’s three-run homer off Twins starter Kyle Gibson in the second. However, in the eighth, Joakim Soria gave up a two-out, game-tying solo home run to Jorge Polanco.

After two scoreless innings from Liam Hendriks, who filled in as closer during Treinen's absence, the A’s had a chance to win in the 10th as Matt Chapman and Matt Olson led off with back-to-back walks. Chapman reached third base later in the inning and tried to score on a one-out chopper to third by Mark Canha, but he was called out on Miguel Sano’s throw to Garver on a close play at the plate. The call stood after a replay review.

“It looked like he was safe to me,” Melvin said. “I don’t know if they have different angles, or more angles, but it looked like he beat it to me.”

Chapman said he felt he evaded the tag from Garver, but he had not yet gone back and watched the replay following the game.

“I know the throw beat me, but when he was going to make the tag, I felt like I snuck my foot in,” Chapman said. “One of those plays that are bang-bang and can go either way. Looking back, that’s a huge play. Just the way it goes.”

More frustrating for Chapman was the offense’s inability to come up with the big hit they’ve delivered so often at home this season. The A’s went 1-for-15 with runners in scoring position, leaving 11 runners on base. They had runners in scoring position in the 11th and 12th, including Chapman at third as the potential tying run in the final inning.

“If you want to be considered one of the best teams, you have to beat first-place teams,” Chapman said. “We won the first game and were in the second one. I like the way we’ve been playing.”

The loss snapped a four-game winning streak for Oakland, which will go for a third consecutive series victory on Thursday afternoon.

Fiers keeps rolling

A poor first month might be the only thing keeping Mike Fiers from a spot on the American League All-Star team. The right-hander continued his strong run by retiring the first 14 batters he faced, finishing his night with two runs allowed (one earned) on five hits with four strikeouts over six-plus innings.

Fiers has allowed three or fewer earned runs in 13 consecutive outings. Since April 26, Fiers’ 2.51 ERA is fourth lowest among AL starters.

Fiers has kept teams guessing by switching up his plan of attack through each start. He began throwing a cutter more frequently in a win against the Angels last week, and he continued to throw it Wednesday night, along with a slider he threw for 22 of his 88 pitches. He got ahead in the count often and didn't issue any walks.

“Just a great mix of pitches. He was elevating side to side with his cutter. Another really good outing,” Melvin said. “These games where he gets into the seventh inning are usually ones we win, just didn’t happen for us tonight.”