Rosenthal allowed a single to the first batter he faced and gave up an unearned run over a career-high 8 2/3 innings as the Class A Quad Cities River Bandits held on for a 3-1 victory over the Lake County Captains.
The Cardinals prospect struck out eight, walked one and hit a batter while facing only three batters over the minimum. He got ahead of Carlos Moncrief, 0-2, before the right fielder lined his third pitch of the game up the middle for a base hit.
"I got ahead on him, threw some fastballs away and tried to work in my changeup," Rosenthal said. "I kept it up in the zone and it was a pretty hittable pitch."
The 21-year-old right-hander retired Jordan Casas on a line drive and retired Alex Monsalve on an inning-ending double play. Rosenthal (4-7) induced 10 ground-ball outs and threw 107 pitches before departing with a man on in the ninth.
"I was just working my fastball and sinker down in the zone," he said. "I was keeping it down in the zone and working both sides of the plate. Give credit to that team. They have good hitters, they tried to adjust to me early and I tried to pound down early."
Closing in on his second complete game of the season and first career shutout, Rosenthal labored in his final inning. Center fielder Michael Swinson committed a three-base error with one out and Nick Bartolone raced home on a wild pitch before Casas walked. Dean Kiekhefer relieved and induced Monsalve to found out to record his second save and complete the one-hitter.
Rosenthal's only complete game came in a losing effort in the second game a doubleheader on April 27.
"I think nerves had something to do with it," the 2009 21st-round Draft pick said. "I knew it was the first time I could get a complete game, but now that I got the jitters out, hopefully I can go out there and stay strong."
Despite owning a losing record, Rosenthal has been solid for the River Bandits, posting a 3.29 ERA in 16 starts. The Midwest League All-Star is fourth on the circuit with 102 strikeouts and ranks ninth with a 1.10 WHIP.
"Just stay healthy and keep developing my off-speed pitches -- the curveball and, especially, the changeup," he said of his plan for the rest of the season. "I feel like a huge part of the game is adjusting to hitters. As you move up, they make adjustments, so I feel like I have to do the same."
Friday was Rosenthal's first win since June 2. In the interim, he had a 2.70 ERA in six starts.
"It's awesome to get a win, but ultimately I try to go out there and pitch as many innings as I can," he said. "I think it's just about getting command of my pitches and learning the game."
Cody Stanley was 4-for-4 with a homer and two runs scored, while Swinson had two hits and two RBIs for Quad Cities.
Captains starter Mike Rayl (5-5) took the loss, despite allowing a run on six hits over six innings.