CINCINNATI -- Rookie right-hander Tyler Glasnow has endured a few rough first innings for the Pittsburgh Pirates, but Monday night was rougher than most. Two walks, a home run and three-run deficit after only three batters.

"I guess I've had a lot of practice with it," Glasnow said. "I didn't get discouraged."

The calming influence of pitching coach Ray Searage and catcher Elias Diaz helped Glasnow recover en route to his first career victory.

Josh Harrison hit a three-run home run, and Glasnow pitched five shutout innings after the first while contributing three RBIs as Pittsburgh rolled to a 12-3 win over the Cincinnati Reds at Great American Ball Park.

"It was fight or flight, and he fought," Pirates manager Clint Hurdle said of Glasnow. "He was able to regroup and refocus on what he needed to do. He stayed on the gas and threw strikes with everything."

Harrison continued to haunt his hometown team with his third home run in two games, and second baseman Alen Hanson went 2-for-3 with a triple and two runs for Pittsburgh, which has won four of six.

Following a rough first, Glasnow (1-1) bounced back to strike out three straight batters in the second inning, then cruised from there. He also reached base three times with a single and two walks.

"He made adjustments (after the first) and he was amazing," said Diaz, who collected his first career hit, a seventh-inning single. "I told him to just compete and get outs. Just keep working. It was a big day for him and me."

Wade LeBlanc earned his first save of the season and third of his career, allowing one hit and striking out three over three scoreless innings.

Joey Votto put Cincinnati ahead 3-0 in the first, but starter Scott Feldman (1-3) couldn't maintain the lead and the Reds let Glasnow off the hook early.

"We weren't able to come up with that second blow," Reds manager Bryan Price said.

Glasnow worked himself into trouble with a pair of walks to begin the first inning. On an 0-1 pitch, Votto launched a mammoth home run that hit near the top of the batter's eye pavilion in center, an estimated 449 feet from home plate. It was Votto's ninth homer this season.

"He went middle up to Votto, where you can't put it," Hurdle said. "He got on a roll after that."

Cincinnati (12-14) had only three hits over the final eight innings.

"Ray (Searage) is super positive," Glasnow said. "He asked me to put my trust in him. The way I am, I take to a coach like that. I elevated a fastball to Votto. He's a good hitter."

Feldman retired the first six batters he faced before Hanson led off the third with a triple and scored on Jordy Mercer's double to make the score 3-1.

Things unraveled for Feldman in the fourth.

Pittsburgh (12-14) went ahead 4-3 on Glasnow's bases-loaded single with two strikes that knocked in two runs.

"The 1-2 (pitch) to Glasnow was a cutter that kind of backed up," Feldman said. "That was the dagger."

If that was the dagger, Harrison twisted the knife when he made it a four-run lead with his third home run in two days, a three-run shot, to put the Pirates ahead 7-3.

Feldman was finished after four innings, having allowed seven runs and six hits over 73 pitches.

"If you look at the game, they scored 10 of their 12 runs with two outs," Price said. "Their pitcher got the hit that extended the inning in the fourth, then Harrison hits the three-run homer."

With the bases loaded against Reds right-hander Robert Stephenson in the seventh, Gift Ngoepe singled off the glove of shortstop Zack Cozart driving in two more runs to make the score 9-3.

The Pirates ultimately scored five runs in the seventh, three on a base-loaded walk, a passed ball and a wild pitch, to blow the game wide open. Blake Wood walked three and uncorked the run-scoring wild pitch in a sloppy inning for the Reds.

"It was just a poorly pitched game tonight," Price said. "We couldn't get anything going. We're certainly better than that. We need to pitch and play better."

NOTES: Reds RHP Anthony DeSclafani (right elbow) was in Cincinnati on Tuesday for a checkup but said there is no timetable for his return. ... Pirates 2B Adam Frazier (left hamstring strain) hit, took ground balls and ran in the outfield on Tuesday. He is expected to begin a minor league rehab assignment at the end of the week. ... Pirates C Francisco Cervelli missed his third consecutive start due to a foot injury.