Marcell Ozuna was seeking to snap out of a slump, so an opposite-field single in the second inning would do. The Pittsburgh Pirates designated hitter — who calls himself a “petroleum guy” — wasn’t done.

He was only getting warmed up.

When Ozuna delivered an RBI double in the fourth inning Tuesday night, not only did it propel the Pirates to rally from a four-run deficit against the Washington Nationals but served as a stop for his scuffles.

“He’s been swinging the bat better,” Pirates manager Don Kelly said. “He’s been working hard, like we talked about. Hopefully, it’s a catalyst for him.”

Ozuna entered the game batting .070 (3 for 43) with 12 strikeouts and five walks — and without an extra-base hit or an RBI — through his first 11 games, prompting Pirates fans to boo the three-time All-Star who signed a $12 million free-agent deal in February.

Despite the 5-4 defeat, the 35-year-old Ozuna finally felt the pressure to produce had been relieved after the jeers turned to cheers at PNC Park.

“The boos and all of that stuff are just hard for a little bit,” Ozuna said. “After you do good, they don’t say anything.”

Ozuna went 2 for 4, also reaching on a throwing error by third baseman Jorbit Vivas with two outs in the sixth inning. Ozuna was robbed of a hit in the eighth when left fielder Daylen Lile chased down his line drive to left-center with Ryan O’Hearn on first base.

“The ball he hit to left-center, the left fielder made a really good play on,” Kelly said. “We just need to stick to that approach, continue to do what we’ve been doing and square the ball up like we did tonight.”

After starting 2 for 31 through his first eight games, Ozuna was withheld from the lineup for the final game of the San Diego Padres series and the opening game at the Chicago Cubs to work on finding his swing.

Kelly and Ozuna played together with the Miami Marlins for 15 games over the 2015-16 seasons, so Kelly knew that Ozuna has a reputation for being a good teammate and a positive influence in the clubhouse — even when he wasn’t producing like he had in the past.

“He cares about everybody in there and he’s going to do anything he can to help his teammates, and he wants to be the guy that gets up there,” Kelly said before Tuesday’s game. “He’s going to get hot and he’s going to be a dangerous bat.”

Kelly’s words proved prophetic against the Nationals, as Ozuna was one of a trio of players batting below the Mendoza Line who had big games. Catcher Joey Bart, who was hitting .105, had a solo shot in the fifth for his first homer. Rookie shortstop Konnor Griffin, who was hitting .152, also went 2 for 4 and doubled off the Clemente Wall in the ninth.

“That’s Marcell. That’s the impact that he has,” Kelly said “It would be really easy to come in on a new team and not be swinging the bat and get down on yourself and that’s certainly not how he’s gone about it at all.”