"Hats off to the other guy," he offered.
Houston's No. 17 prospect struck out eight over six scoreless innings, but his supporting cast was silent with the bats in the Class A Lexington Legends' 3-1 defeat to the Kannapolis Intimidators.
Tropeano scattered four hits and two walks, lowering his early ERA to 0.82.
"I was just trying to attack the zone," he said. "I had command of my fastball and mixed in my secondary pitches."
The 21-year-old right-hander also pitched well without winning in his season debut on Monday. He limited Hagerstown to a run on four hits over five innings and sat down a career-high 10 on strikes. He shares the South Atlantic League lead with 18 strikeouts in 11 innings.
"I'm just going to keep going after it," Tropeano said.
The Astros' fifth-round Draft pick out of New York's Stony Brook University last June fanned nine over six two-hit, scoreless innings in his previous best effort, a July 24 victory in the New York-Penn League. He won three of his first five pro decisions, compiling a 2.36 ERA in a dozen outings at short-season A Tri-City in 2011. Comparing the hitters he faced in the New York-Penn League to those he in the South Atlantic, he said they're noticeably more aggressive.
The Intimidators scored three times after Tropeano's exit, plating a run in each of the final three frames. Mark Haddow homered off reliever Nathan Pettus in the seventh, Kevan Smith doubled in Michael Johnson in the eighth and Collin Kuhn delivered an RBI double in the ninth.
Leadoff man Delino DeShields Jr., the Astros' No. 8 prospect, singled, stole second, advanced to third on a wild pitch and eventually scored the Legends' lone run on Alex Todd's sacrifice fly in the eighth.
DeShields also walked in four plate appearances and is batting .293 this season.
"One of those scrappy players with power. He's also a great defender," said Tropeano, who recorded six groundouts. "I love pitching in front of these guys."
Kannapolis starter Keith Vance (1-0) -- that "other guy" -- allowed three hits and struck out five over six shutout frames.