The Rays' No. 4 prospect struck out seven and allowed three hits over five scoreless innings Friday night as short-season Hudson Valley pulled out an 8-7 victory over Aberdeen.
Guerrieri hit two batters and faced four over the minimum in his 10th start for the Renegades. He struck out the last two batters he faced but did not figure in the decision.
"Fastball command was good," he said. "Curveball command was good, too. I was throwing it for strikes. It turned into a good outing for me."
The 19-year-old right-hander is 1-2 with a 1.07 ERA that would lead the New York-Penn League if he had enough innings to qualify. He's allowed 32 hits over 42 innings while striking out 37 batters and walking only two. Over his last four starts, the South Carolina native has given up just one earned run.
"Just getting ahead of guys and staying ahead and working the fastball until they can prove they can hit the off-speed," Guerrieri said of his success. "First-pitch strikes help out a lot and no walks. That's really been the key to my success, command of all my pitches."
Guerrieri -- MLB.com's No. 81 overall prospect -- also credited his third pitch, the changeup.
"I've been throwing it a lot this year. It's the pitch I've been working on most and it's turned into a pretty good pitch," he said.
Drafted 24th overall by Tampa Bay last year, Guerrieri spent the early part of the season in extended spring training and did not make his professional debut until June 20.
"I couldn't ask for a better first season, professionally," he said. "I'm very satisfied with it and I think extended spring training really helped. It's been a good experience for me; I wouldn't change anything."
Jose Molina (3-1) earned the win in relief, allowing two hits over 1 1/3 scoreless innings. Ryan Garton recorded the final four outs, fanning two, for his fifth save.
Luke Maile had two hits, scored twice and drove in a run for the Renegades, while Leonardo Reginatto collected three hits.
Creede Simpson homered and drove in two runs for the IronBirds.