MINNEAPOLIS (AP) — Zach Stewart’s sinker and slider were tumbling over the plate. He stood tall and stayed steady on the mound.

The Minnesota Twins couldn’t hit his pitches. The Chicago White Sox couldn’t stop praising the rookie’s composure.

Stewart took a perfect game into the eighth inning and finished with a one-hitter as the White Sox completed a doubleheader sweep of the Twins with a 4-0 victory on Monday night.

“It was a lot of fun. It was just one of those things,” Stewart said. “In the ‘pen, the ball was coming out good. I could tell it was going to be somewhat of a good night. I didn’t know it was going to be that good. But it just felt good from the beginning.”

The Twins were 21 up and 21 down against Stewart until Danny Valencia’s leadoff double in the eighth spoiled the right-hander’s bid to become the 21st rookie in major league history to throw a no-hitter.

“He didn’t really have stuff that was overpowering. He was just locating really well,” Valencia said. “He had all his pitches going, and he was throwing everything for a strike.”

The 24-year-old Stewart (2-3), whose only previous major league win came at Target Field last month, struck out nine in the first complete game of his career.