Lewis said he felt good after throwing 47 pitches for Frisco but he wasn't pleased with the results, particularly with the velocity of his fastball.
Lewis topped out at 87 mph and was mostly around 85-86 mph, throwing his fastball almost exclusively. The right-hander said he wants to get to 91 mph.
Lewis has at least two more rehab starts in the minors, the next one coming for Frisco in Tulsa or for Triple-A Round Rock in Memphis on Saturday or Sunday.
"I'm trying to get to where I can get big league hitters out," he said. "In my mind, I don't think I can do that yet."
Lewis allowed two runs on four hits, all in the third inning, against the San Antonio Missions and threw 33 strikes. He had three strikeouts and no walks. He said he was pleased with his location but needs to generate more power.
"I definitely need more reps," Lewis said. "I definitely need to get my arm strength up. Throwing 85 or 86 isn't going to cut it."
Todd Wills is a contributor to ESPNDallas.com.