The right-hander lasted just five innings, surrendering four runs on six hits and three walks with two strikeouts. He remained winless in 13 career starts, and fell to 0-6 with a 7.06 ERA in nine outings this year.
"Looking back, it wasn't exactly how I wanted it to go," said Hendriks, who threw 97 pitches. "But I made some good pitches and they had some hits on pitches that were down. They also had some hits on bad pitches, but there were a couple that weren't crushed or hit that well. So I just have to remember I was decent and that I need to remember what I figured out during the game with my mechanics."
He had trouble from the start, as he walked the first batter he faced in Coco Crisp before throwing a wild pitch that allowed Crisp to reach second. Crisp came around to score on a single from Josh Reddick.
Hendriks ran into more problems in the third, when he gave up a two-run single to Yoenis Cespedes with the bases loaded and one out. Oakland scored again in the fourth on an RBI double from Crisp after Cliff Pennington led off the frame with a double.
"He's got to locate the ball better, just like we talked about, and get his pitches over better," Twins manager Ron Gardenhire said. "He threw a lot of pitches; a hundred pitches in five innings is a lot of pitches. Like I said, he competed. He didn't let the innings get too out of hand. He gave up a few runs here and there, but you have to be a little bit better than that with the strike zone and work ahead of more hitters."
It was more than enough support for A's left-hander Tommy Milone, who gave up just one run on two hits and a walk over eight strong innings.
The Twins scored their lone run against Milone on an RBI groundout from Drew Butera to score Ryan Doumit, who reached earlier on a popup single that first baseman Chris Carter lost in the sun.
Milone was able to remain effective despite the fact that the A's tied a season high by committing four errors.
"Typically, you don't win when you make four errors and Milone is one who has let that bother him in the past," A's manager Bob Melvin said. "Today, Milone didn't let that effect him. He went out and picked up his teammates, where we weren't too good in the field."
Oakland added an insurance run in the seventh on a solo homer from Crisp off left-hander Tyler Robertson. Right-hander Ryan Cook struck out the side in the ninth to preserve the victory for Oakland, which won two out of three against Minnesota.
The loss was the Twins' 11th over their last 13 games and dropped them to a season-worst 21 games under .500.
"Just a bad day for us, and it's too bad we lost the series," Gardenhire said. "A thin offensive day for us. Milone was pretty good. He changed speeds, located his fastball in and out, lots of good changeups and breaking balls. He kept us off balance pretty much the whole day."