MIAMI -- Down the stretch, the Marlins are looking to see which prospects take advantage of opportunities.

On Thursday night, a couple of rookies made strong impressions. From the pitching side, Robert Dugger impressed over seven innings in his second big league start. But the game ultimately was decided by one swing from outfielder Harold Ramirez, who connected on a walk-off homer in the 12th inning that lifted the Marlins to a 4-3 victory over the Reds at Marlins Park.

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“Any time we get a win right now feels good,” Marlins manager Don Mattingly said after his club avoided a four-game sweep at the hands of Cincinnati. “Guys get to experience that. Harold has been here for a while now. Robert is in a little bit different situation. We will get a decent look at him this last month and see what it is.”

All four of Miami’s runs came via solo shots, with Ramirez going deep to left field off Raisel Iglesias to open the 12th.

“I'm really just trying to get on base,” said Ramirez, who connected on a 1-1, 95 mph sinker. “I know we just needed one run. They needed me on base. I got that pitch. I hit a home run. I'm just kind of enjoying it now.

“I'm going to give 100 percent every day. Every day, they're giving me an opportunity. I want to go out there and play hard. If I play hard, I know I'm going to get another opportunity the next day.”

The Marlins went 1-6 against the Reds in the season series, but they ended up having reason to celebrate. Miami improved to 6-6 in extra innings, and Ramirez has become a walk-off regular. The homer was his third walk-off RBI of the season. He also hit a walk-off shot on Aug. 1 against the Twins.

Along with Ramirez’s big blast, the Marlins received a strong start from Dugger, who allowed two unearned runs in seven innings.

The Marlins used three solo home runs off Alex Wood to claim a 3-2 lead, which stood until Aristides Aquino’s two-out RBI single in the eighth off Ryne Stanek.

Starlin Castro connected in the sixth, Austin Dean knocked a drive to left to knot the score at 2 in the fifth and Jon Berti led off with a home run for the third time this season.

Dugger showed his resolve with two outs and runners on the corners in the seventh. Jose Iglesias engaged in a 13-pitch showdown, fouling off nine straight pitches and working the count full before Dugger got him swinging through the only slider he threw in the at-bat.

"That was a battle for the ages,” Dugger said. “We finally mixed in a breaking ball there at the end. He was in swing mode with the fastball. He swung over it.”

The game didn’t start off smoothly for the Marlins. With one out in the first inning, center fielder Lewis Brinson dropped Joey Votto’s fly ball to the warning track. It went for a two-base error, and Aquino crushed an 0-1 curveball for a two-out, two-run homer.

Aquino’s 14th homer accounted for two unearned runs. But after that, Dugger didn’t permit a hit until Aquino’s liner to third ate up Castro to lead off the seventh.

The 24-year-old Dugger made the start in place of Jordan Yamamoto, who was placed on the 10-day injured list with a right forearm strain. The Marlins were planning on making Dugger a September callup, and Yamamoto’s injury expedited the process.

In Dugger's other big league start on Aug. 5 in the first game of a doubleheader against the Mets, he allowed a home run to Jeff McNeil on his first pitch and six runs total over five innings.

Ranked by MLB Pipeline as Miami’s No. 24 prospect, Dugger split time this season between Double-A Jacksonville and Triple-A New Orleans. His combined Minor League totals were 8-10 with a 5.15 ERA in 23 starts. But at Jacksonville, he was especially effective, going 6-6 with a 3.31 ERA in 13 starts.

“Just be ready for the moment,” Dugger said. “They can call your name at any time. I was down in the Minors working on my craft. When I got the call, just be me, do my job.”