CHICAGO -- Zac Gallen ventured into uncharted territory in his MLB career on Wednesday night, and took a big step forward in staking a claim to be a rotation regular with the Marlins.

The rookie right-hander established big league highs for innings (seven) and strikeouts (nine), as well as a low for hits allowed (two), in the Marlins’ 2-0 victory over the White Sox at Guaranteed Rate Field. Making his sixth MLB start, Gallen (1-2, 2.76) collected his first win.

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“He's a kid who is pretty good about his makeup,” Marlins manager Don Mattingly said. “He's pretty easy going. He's steady. He's a guy that's smart. He already knows how to pitch to a game plan. He's a mature kid for a young pitcher.”

César Puello provided the big blast, a two-run homer off Reynaldo Lopez with one out in the eighth inning. After losing the series opener on Monday, Miami rebounded to take the series.

“Any time you make it more than five innings is good,” Gallen said. “That's kind of been my thing the last couple of starts. I like playing. I like being out there. I'm kind of glad being out there and helping the team get a win.”

Closer Sergio Romo worked around two singles in the ninth and logged his 17th save.

Miami capped its road trip at 2-4 after getting swept by the Dodgers, and losing 9-1 in the series opener against the Sox.

Puello’s home run, his first since joining the Marlins, was projected by Statcast at 432 feet, with an exit velocity of 105.5 mph. With one on for the White Sox in the eighth, Puello also made a run-saving catch at the wall in center on Jose Abreu’s two-out drive off Nick Anderson.

“Just before that play, our coaching staff was saying, ‘Play no doubles,’" Puello said. “I’m thankful we got the result.”

The emergence of Gallen, who followed up left-hander Caleb Smith’s seven-inning gem on Tuesday in Miami’s 5-1 victory, further demonstrated the quality of starting pitching the Marlins are assembling.

“There's sort of a competition [among the Miami starters],” Gallen said. “If one guy does better, you kind of want to one up him. At the same time, you can pick up stuff that he [Smith] did last night. Even though he's from the other side, there are still things that you can gauge their approach, and I think that helped me tonight.”

In regards to their long-term plan, the Marlins are open to moving a controllable starter before the July 31 Trade Deadline, which is a week away. Romo, a free agent after the season, is also potential trade target for teams.

Smith, another rumored name, retired the first 17 he faced and had his no-hit bid broken up in the sixth inning on Tuesday, while right-hander Trevor Richards has attracted interest as well.

“Those last two arms that they've had have been pretty good,” White Sox manager Rick Renteria said. “Albeit, you look at the velocities, 93, 94. Well, they've got a lot of life to their fastballs and their breaking balls are pretty sharp. In watching both yesterday and today, they're pitching with some confidence, they're attacking the strike zone.”

Gallen’s start also revealed another obvious area of need for the Marlins. The organization lacks offensive punch and is open to at least listening on its controllable surplus starters, if they can acquire an impactful hitter.

Gallen bookended the six-game road trip, taking the ball last Friday at Dodger Stadium. In both starts, the rookie showed the kind of promise to become a mainstay in the rotation.

Even though he suffered a loss against the National League West-leading Dodgers last week, Gallen allowed just one earned run (two total) in 5 1/3 innings in a game Miami lost 2-1.

“There was definitely sort of confidence after that,” Gallen said. “I didn't feel the best [at L.A.]. I thought I had good stuff. Today, it all came together, it was nice.”

The 5 1/3 innings were personal high for Gallen until Wednesday.

Gallen opened the season at Triple-A New Orleans, and dominated the Pacific Coast League, going 9-1 with a 1.77 ERA. He earned his first big league promotion on June 20 against the Cardinals, the organization that took him in the third round of the 2016 MLB Draft.

“We've been pretty resilient all year,” Mattingly said. “In the L.A. series, we had a chance to win a couple of games in there, and didn't do anything with them. That first game [in Chicago], we talk about pitchers' momentum as a starter. We were behind early. Just never got anything going. Then we bounce back and play good the next couple of days, that's good.”