Foltynewicz (1-1) struck out eight batters over six shutout innings, and the Legends topped the host Hagerstown Suns, 3-0. He scattered three hits and two walks, retiring his final six batters.
The 20-year-old right-hander, Houston's first-round draftee in 2010, yielded six runs -- two earned -- on eight hits over 2 2/3; frames in his season debut Friday. He won five of 16 decisions and compiled a 4.97 ERA in 26 starts for the club in 2011.
Batting third at designated hitter for Hagerstown, Nationals' rehabbing outfielder Rick Ankiel singled and walk in two plate appearances against Foltynewicz before he was replaced by pinch-hitter Billy Burns in the fifth. Ankiel, who is recovering from a tight left quadriceps muscle, homered in his debut for the team on Monday.
Suns starter Brian Dupra (0-2) gave up two runs -- one earned -- on five hits over six innings.
Lexington designated hitter Zachary Johnson led the Legends offense, collecting two hits and two RBIs in four at-bats. Leadoff man Delino DeShields Jr., the Astros' No. 8 prospect singled once among his four at-bats, leaving his batting average through seven games at .286.