Right-hander David Phelps tossed two hitless innings of relief for Miami, walking one.
The Cardinals are looking for Martinez to step up and win the fifth starter spot. In his two-inning stint, the hard-throwing right-hander didn't disappoint. He retired all six he faced, with three strikeouts. He threw 29 pitches, with 22 strikes.
An anticipated matchup was Martinez bringing the heat against Stanton, who is wearing a protective mask.
Martinez retired Stanton on a routine fly ball to left in the first inning, and his fastball was clocked at 95-96 mph in the sequence.
Dan Haren got the start for Miami, and he gave up two runs on three hits in two innings.
"It seems so early in spring to be out there throwing two innings when the season doesn't start in over a month," Haren said. "I feel OK. I felt really good coming into camp, body-wise. My body's dragging right now a little bit. My arm's dragging a little bit. When you're young, you have 'dead arm.' When you're old, you have 'dead body,' so I have dead body right now."
Haren had a tough-luck first inning, giving up a two-run, opposite-field single to Adams. Jason Heyward started the one-out rally with a single that deflected off the glove of first baseman Michael Morse.
Haren fell behind 3-1 in the count to Heyward, who ripped a liner that Morse wasn't able to corral. It was scored a hit.
Matt Holliday delivered a ground-rule double to left on a ball that Christian Yelich lost in the sun. Adams floated his two-run single to short left field.
St. Louis added two more runs in the top of the seventh on a Rafael Ortega grounder and Greg Garcia double.
Miami's first hit came in the fourth inning, on Dee Gordon's bunt single. The Marlins' only run came in the eighth on an RBI single by Jhonatan Solano.
Up next for the Marlins: Tom Koehler, vying for the fifth starter spot, gets the nod on Friday afternoon at 1:05 ET against the Red Sox in Fort Myers, Fla. The right-hander is scheduled to throw two innings. Brad Hand, also in the mix for a rotation spot, will pitch in relief. Among the regulars making the trip are center fielder Marcell Ozuna and Morse. Jeff Mathis will catch.