MINNEAPOLIS -- It’s amazing how one pitch can completely flip a game around.

After cruising through six innings of one-run ball, Mike Fiers went out for the seventh carrying a two-run lead and looking to put the cherry on top of a night that had him in line to move to the top of the pack with the lowest ERA among American League starters since April 26. Instead, Fiers allowed two runners to reach base, departing with one out to be replaced by Yusmeiro Petit, who surrendered a first-pitch three-run home run to Twins pinch-hitter Eddie Rosario.

“He’s been the guy that’s been getting it done for us in that situation all year,” A’s manager Bob Melvin said of Petit. “Every now and then you’re going to give one up.”

• Box score

What had been a winning formula so often for the A’s this year backfired on Thursday night as they fell 6-3 to the Twins and snapped a six-game winning streak. The loss also puts them in a tie with the Rays for the second American League Wild Card spot.

The second-guessing is sure to come with Melvin pulling Fiers at just 89 pitches, but the matchup he went for was one that favored Oakland. Rosario was hitless against Petit in his four previous at-bats before unloading on the first-pitch fastball that bounced off the frame of the second deck in right field and sent the crowd of 28,432 fans inside Target Field into a frenzy.

“It’s a hot night and [Fiers] is back out there for the seventh inning, gives up a hit and a walk, so that’s the situation we usually bring Yusmeiro in,” Melvin said. “Gotta give Rosario credit. He hit a good pitch.”

Petit had also been going as good as any A’s reliever outside of All-Star closer Liam Hendriks of late. The right-hander entered the night having turned in scoreless outings in 13 of his past 15 appearances and holding a 2.33 ERA, which was eighth lowest among non-AL closers. But if there is one spot where he’s struggled this year, it’s the long ball. Rosario’s homer was the ninth given up by Petit this year, tied for third-most by AL relievers.

Given the situation -- runners on first and second -- Petit said he was looking for a ground ball that could produce an inning-ending double play. The fastball did not appear to be in a bad spot as it traveled low in the zone, but he was hoping to get it more towards the outer corner. Instead, it was left right in the middle.

“The ball moved a little bit over the plate, and I paid the price for that,” Petit said. “I think it was a little bad luck because I feel good and my arm felt good. I just missed the location and lost the game.”

On a toasty night that saw the temperature at 87 degrees at first pitch with 90 percent humidity, Fiers admitted to feeling a little more exhausted than usual as he battled the elements while adding he felt he still had the velocity and stuff to finish the seventh inning. But he did himself no favors by issuing a walk to Miguel Sano, his final batter, even though that might have been more out of pitching with caution against a dangerous Twins lineup, whose 174 home runs entering the night led the Majors.

“A couple of balls got away trying to hit the corners and be too fine. I didn’t want to give them too good of a pitch,” Fiers said. “They have a good lineup over there, and I knew they were going to be swinging so just trying to keep the ball out of the middle of the plate. With a team like that, you have to be pretty careful.”

Fiers increased his streak of consecutive starts in which he’s allowed three earned runs or fewer to 15. He did so pitching around some traffic that was at times self-inflicted, issuing four walks after he had walked a total of two batters over his previous three outings thanks an ability to produce more ground balls than usual, including three that led to double plays.

“For a guy who’s a fly-ball pitcher, he’s found a way to get a ground ball when he needs it,” Melvin said. “The cutter has been a good pitch for him, and he pitched another really good game for him.”

While Fiers did not get the loss, that wasn’t fair consolation for the A’s, who dropped the type of game they’ve been used to winning so often.

Profar stays hot

Jurickson Profar was emerging as one of the heroes of the game before Rosario's homer when his two-run home run off Twins starter Kyle Gibson put the A’s ahead, 3-1, in the sixth inning.

With a recent decrease in playing time after Melvin indicated that Franklin Barreto would be getting the majority of starts at second base a couple of weeks ago, Profar has responded well coming out of the All-Star break, now 4-for-12 with four home runs and seven RBIs in that stretch. He has homered three times in his last two starts.

“He’s been hitting some homers, period. But it seems like he’s just getting some better at-bats right now,” Melvin said. “He’s also looking more comfortable at second base and making some good plays. I don’t know if that has anything to do with the offense, but he’s playing well right now.”