CINCINNATI -- Astros right-hander Spencer Arrighetti earned American League Rookie of the Month honors for August after posting a 1.95 ERA in five starts.

But the 24-year-old hit a bump in the road in his first September start, allowing nine runs on six hits and three walks in the first inning of the Astros’ 12-5 loss to the Reds on Wednesday night at Great American Ball Park.

“They were on all his pitches,” manager Joe Espada said. “They were not fooled. He’s a competitor. He wants to do well. He’s been throwing the ball phenomenal for us. Just not his night. That’s one you want to put behind you.”

Leadoff batter Jonathan India ended Arrighetti’s 14 1/3-inning scoreless streak with his 11th career leadoff homer on a 1-0 pitch.

Elly De La Cruz doubled, singled, scored twice and had two RBIs in the inning. Amed Rosario drove in two runs with a double.

Arrighetti exited after retiring only two batters. He threw 38 pitches (23 strikes).

Arrighetti’s frustration showed on the mound with some shouts into his mitt, and it still was evident after the game.

“There’s a lot to learn when you get your butt kicked,” Arrighetti said. “It’s easy to not learn anything when you’re rolling hot. When you do hit the bump in the road, it’s the most important time to really break it down.”

There were only a few bright spots for the Astros.

Alex Bregman returned to the lineup after missing four straight games with a recurrence of elbow soreness. He started at third base and batted cleanup, going 1-for-2 with a double and a run scored.

“He didn’t play for five days. then he comes out of the gate with a double to right field,” Espada said. “That’s a good sign.”

The Astros’ bats woke up late, but they couldn’t put together a rally.

Zach Dezenzo singled with the bases loaded to drive in two runs in the sixth. Jon Singleton hit a solo homer, his 13th, off Brent Suter in the seventh.

Arrighetti’s rough first inning was in stark contrast to his previous five outings. He carried a no-hitter into the eighth inning in his most recent start Wednesday in Philadelphia and fanned 11.

“Obviously, I’m proud of the way I’ve learned to throw the ball during the course of the year,” Arrighetti said. “Today doesn’t in any way define me as a pitcher. It was a bad outing. It was a bad day for me. I’ll learn and I’ll get better.”

There aren’t many bad outings among Arrighetti’s 25 starts. He allowed seven runs in three innings in his debut on April 10, an 11-2 loss at Kansas City. His shortest outing prior to Wednesday was on June 15 against the Tigers, when he allowed seven runs in 1 1/3 innings.

Even coming off one of the best months for any rookie pitcher, Arrighetti said he won’t just brush Wednesday’s first inning aside and treat it as a blip on the radar. Instead, he plans to take a hard look at why the Reds had so much success against him so early.

“You don’t get out of the first as a starter, it stinks,” Arrighetti said. “I’ll break it down tomorrow. I’ll come back to it logically and I’ll try to figure out the reason why it was seemingly pretty easy for them to hit the ball tonight.”