OAKLAND, Calif. (AP) -- Tanner Roark has been so effective since tinkering with his mechanics and going with a quicker delivery that the Cincinnati right-hander realized things were off when he slowed down in the fourth inning.
It didn't take long for Roark to speed up again and get back on track, setting the tone for Cincinnati's first win against an American League team this season.
Roark and three relievers combined on a six-hitter, Derek Dietrich continued his power surge with another home run, his fifth in six games, and Cincinnati blanked the Oakland Athletics 3-0 on Thursday to snap a 10-game interleague losing streak.
''Tanner came up for us today and went deep into the game and really pitched a great game,'' Reds manager David Bell said. ''He was getting ahead and he was making pitches with two strikes. He was able to put guys away once he got ahead.''
Roark (3-1) allowed three hits over six innings and got the A's to hit into a pair of double plays while winning his second consecutive start. Roark walked two, struck out three to lower his ERA to 3.27.
That's significant after Roark scuffled through the first month of the season with a 4.08 ERA. Since altering his delivery, Roark has a 1.42 ERA in two May starts.
''Working quicker, getting the signs and going has helped out a lot,'' Roark said. ''I felt myself getting away (from) it in the fourth and then I came back in the fifth and I recognized it, which is good. If I focus on my tempo being quicker then I know my delivery's going to be quicker and it will set me, my pace.''
Amir Garrett retired two batters, David Hernandez set down four and Raisel Iglesias pitched through a shaky ninth for his seventh save in nine tries.
Iglesias walked Kendrys Morales and gave up a two-out double to Chad Pinder but got Ramon Laureano to foul out, securing Cincinnati's fourth shutout this season.
''All around a well-pitched game and a lot of good defensive plays,'' Bell said. ''We got what we needed with the two home runs, which was good to see, but the story of the game was pitching and defense.''
Eugenio Suarez homered, doubled twice and made a pair of defensive gems for the Reds. The Cincinnati third baseman fielded Laureano's sharp grounder down the third base line in the third inning then made a leaping throw across his body to get the out. In the fourth, Suarez snared Matt Chapman's liner and doubled up Jurickson Profar off first base.
Cincinnati entered the day 148-209 in interleague games with a league-worst .415 winning percentage. The Reds hadn't beaten an American League team since a 7-4 victory over the Cleveland Indians on July 10, 2018. They were no-hit by Mike Fiers in the first game of this series against Oakland on Tuesday then lost 5-4 in 13 innings Wednesday.
''It's good to get that monkey off our back,'' Roark said.
Suarez doubled and scored when Dietrich lined an 0-2 pitch from A's starter Chris Bassitt into the right-field stands in the first inning. Dietrich, who homered four times in the Reds' four-game series against the Giants over the weekend, raised his right fist and celebrated even before the ball cleared the fence.
Suarez homered in the third to make it 3-0 then doubled again in the eighth but was thrown out trying to steal third.
Bassitt (1-1) allowed three runs, walked one and had nine strikeouts in 7 2/3 innings.
''Four or five mistakes the last couple of outings and I feel like four or five mistakes have been all home runs,'' Bassitt said. ''It's frustrating but at the same time, tip your hat. They're really good hitters.''
SHOULD HAVE STAYED PUT
Jose Peraza reached on a bunt single in the fifth then took off running when catcher Josh Phegley's throw sailed past first base into the Reds bullpen for an error. Right fielder Stephen Piscotty retrieved the ball then threw to Gold Glove third baseman Chapman, who collided with a sliding Peraza well short and wide of the bag. Chapman easily tagged Peraza out.
Athletics: DH Khris Davis was rested because of a sore left hip. ... 1B Mark Canha (sprained right wrist) will begin a rehab assignment with Triple-A Las Vegas on Friday.
Reds: RHP Luis Castillo (3-1, 1.97 ERA) faces the San Francisco Giants for the second time in six days Friday at Oracle Park. Castillo gave up four runs in seven innings and had a no-decision against the Giants on Sunday.
Athletics: RHP Frankie Montas (4-2, 2.75) goes against the Cleveland Indians in the opener of a three-game series at the Coliseum on Friday. Montas has allowed three or fewer earned runs in each of his seven starts this season.
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