Brewers manager Ron Roenicke said a few starts in a row is a chance for Thornburg to prove he belongs in the future starting rotation plans.
"Absolutely," Roenicke said. "But we'll see with him. He's got enough stuff to do it; it's just command and confidence. So we'll see what he can do out there."
Thornburg entered the season as the Brewers' top prospect but he struggled mightily in 15 starts with Nashville, pitching to a 0-9 record and 5.79 ERA. Oddly enough, he has pitched well in six relief appearances and one start with the Brewers, holding a 2.22 ERA in 24 1/3 innings.
Thornburg started the nightcap of Tuesday's doubleheader in Chicago and turned in the best start of his young career, tossing six scoreless innings, allowing four hits and striking out six.
"I think it's a case of not trying to do too much, honestly," Thornburg said. "I try not to think about wanting to get in the rotation. I pretty much try to concentrate on each outing and doing the best I can when I'm out there. But I'm definitely pleased with this opportunity."
Thornburg said he talked to veteran right-hander Kyle Lohse about the mental aspect of pitching, which helped him simplify his approach.
"Pretty much staying under control," said Thornburg of the topic of his conversation with Lohse. "Concentrate on making your pitch, don't worry about the hitter. Whether you need to locate a fastball down and away, you're going to locate a fastball down and away. You're not worrying about trying to beat his bat. You're not trying to blow it by him or anything like that. You're trying to make your pitch and everything past that is chance."
Roenicke said he will reevaluate the rotation after Gallardo and Marco Estrada return from the DL. Estrada made a rehab start with Nashville on Friday, which Roenicke said was to last 45-50 pitches.
Kevin Massoth is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.