After making a couple of shaky starts, José Ureña took the mound on Thursday afternoon with something to prove. The 28-year-old was aiming to show he should be a fixture in the Marlins' rotation, especially if they reach the postseason.

Ureña backed that up with 5 2/3 strong innings. But a nine-pitch showdown in the sixth inning resulted in a two-run single by Kevin Plawecki that provided the Red Sox with a lift in their 5-3 victory over the Marlins at Marlins Park.

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With playoff implications on the line, Miami manager Don Mattingly said before the game that he was looking for more from Ureña, the club's most experienced starter. The Marlins (25-23) dropped two of three, and they now brace for a five-game series with the Nationals, which includes doubleheaders on Friday and Sunday.

"We need this guy to be like the other guys," Mattingly said pregame. "He's one of our big boys. He's got to be able to go five, six innings every time. You've got to feel like you're going to get a good outing every time out. Not kind of put your bullpen in jeopardy."

With 12 games to play over the final 10 days, the Marlins find themselves three games back of the Braves in the National League East.

Matched against former Marlin Nathan Eovaldi, Ureña did his part. In the first inning, he worked out of a first-and-third jam with no outs -- logging two strikeouts and a popout.

"No question," Mattingly said after the game. "I thought José was really good today. The ball had a lot of movement, and more down than that sideways movement. I thought he was really good. He gets out of that first, and that's one of those things I mark on my card. That's kind of a game-changing inning, getting out of that."

Ureña, in his first two starts since coming off the IL, had allowed eight earned runs in 9 1/3 innings.

How the game started made fans wonder if it would be another rough outing for Ureña. Alex Verdugo and Rafael Devers each singled to put runners on first and third with no outs. Ureña then fanned Xander Bogaerts and J.D. Martinez. The inning ended when Plawecki popped up a sinker to catcher Chad Wallach.

"That was a huge inning for me, to get out of there," Ureña said. "I tried to strike out one of those hitters and see if I could get a ground ball to get a double play. That was the mindset all the time. After I got that second out, I tried to throw my two-seamer in, and we got a popout there."

Eovaldi, meanwhile, held the Marlins without a hit until Garrett Cooper's leadoff double in the fifth.

Plawecki's two-out single in the sixth opened the scoring. The battle was nine pitches, and Ureña's 76th and final pitch was a 94.8 mph sinker that Plawecki pulled through the left side of the infield for a two-run single.

Ureña kept working Plawecki in with sinkers or two-seam fastballs. He threw a 2-2 slider that was just off the plate and was called ball three. With the count full, Ureña went back with the sinker, and the Red Sox's catcher pulled it for his two-run single.

"I threw a couple of sliders to different hitters, and like J.D., I didn't get a call in different situations," Ureña said. "I didn't want to waste a pitch. I felt that was my best chance. If he's going to beat me, beat me with my two-seamer. That's the thing they couldn't handle the whole night. I preferred that with that [situation]."

Down by two in the seventh, Devers crushed a three-run homer off rookie Johan Quezada, giving Boston a 5-0 lead.

The Marlins chipped back with three runs in the bottom of the seventh. Jorge Alfaro hit a pinch-hit RBI single, while Wallach delivered a run-scoring double and Starling Marte added an RBI groundout.

Mattingly explained why he went with Quezada, who was making just his third big league appearance.

"We were down a couple, and I can't chase every game with my back-end guys," Mattingly said. "I know the usage of our guys and where games are going, I can't chase every game, being behind two runs and trying to use those guys. We had guys down today. There's times like that where everybody out there is going to have to do their part and keep the game where it's at."

Looking to preserve as much pitching as possible, rookie Nick Neidert covered the eighth and ninth innings, allowing one hit with three strikeouts. Neidert, a starter throughout his Minor League career, is being groomed for any role. He's a multi-innings candidate out of the bullpen, and he still is stretched out enough to start, if necessary.

"It's a new role for me," Neidert said. "I've never thrown out of the 'pen before. When I was in Jupiter, [Fla.], I was building up to be a starter, getting innings underneath me. I can be that long-relief help in the 'pen. I can start games, if need be. I just want to be ready for whatever they ask me to do. If it's to pop into the rotation and start some games, I have some length to do that. Also to do long relief or whatever kind of role it is, I'll be ready for that."