The 19-year-old native of the Dominican Republic allowed two runs on four hits over six innings as the Class A Advanced Palm Beach Cardinals beat the Bradenton Marauders, 9-3. He struck out seven, issued four free passes and hit a pair of batters for the victory.
"I felt good, but in the beginning I was a little bit anxious," the St. Louis farmhand said through a translator. "Once the game got going, I was able to relax and focus on my pitches and movement.
"It felt good to know that I could pitch in this league, and now I will work hard before my next start."
MLB.com's No. 3 Cardinals prospect loaded the bases in the first inning on a pair of singles to Robbie Grossman and Adalberto Santos and a walk to Pedro Alvarez, but he escaped unharmed when Evan Chambers grounded out to end the threat.
He stranded Elevys Gonzalez in scoring position in the second frame after the third baseman had drawn a one-out walk and advanced to second on an errant pickoff throw. He also worked around shortstop Ted Obregon's two-out fielding error in the third.
After a perfect fourth, Martinez yielded a leadoff single to Benji Gonzalez in the fifth, walked Robbie Grossman and hit Alvarez to load the bases for the second time. He extinguished the flames, however, by inducing Aaron Baker to hit a tapper back to the mound to start a 1-2-3 inning-ending double play.
"I was feeling the pressure a little in the first inning, but I kept the ball down and got out of the inning," Martinez explained. "In the fifth, I got the bases loaded, but I went back to my breaking ball and got the ground ball for the double play."
Martinez was not as fortunate in the sixth. He hit Adalberto Santos to start the inning, moved him to second on a wild pitch and walked Chambers. Carlos Paulino singled home Santos with a line drive to left field and Benji Gonzalez plated a second Marauders run on a groundout with one out in the inning.
"I felt good going into the sixth inning, but because I had struck a lot of people out, my pitch count was up," he explained. "The biggest difference between here and Quad Cities was that in Quad Cities I was using my fastball more, but here I am using my breaking balls -- my curve and my change-up -- more."
Martinez was 3-2 with a 2.33 ERA in eight starts with the the River Bandits of the Midwest League prior to his promotion. He allowed one run or fewer in six of his starts and he struck out 50 batters over 38 2/3 innings.
He threw four hitless innings in his pro debut -- Quad Cities' 1-0 win over Wisconsin on May 7, fanned nine batters over five three-hit frames in a 7-4 win against Cedar Rapids on May 20 and struck out eight over six shutout innings in a 5-0 blanking of Clinton on June 14.
Arquimedes Nieto, playing in just his third game of the season and second since returning from the disabled list, replaced Martinez in the seventh. He allowed a run on a hit and two walks over two innings before turning over the game to Keith Butler, who struck out the side in the ninth.
"This was just my second appearance of the year since coming back from my rehab, but I was feeling good," Nieto said. "I was able to set guys up with my fastball and then go to my best pitch, which was my change-up."
Former third-rounder Niko Vasquez paced the Cardinals with two homers -- including an eighth-inning grand slam -- and five RBIs.
Nathan Baker (4-5) took the loss for Bradenton, allowing three runs on four hits and a walk while striking out eight over six innings.