PITTSBURGH -- Trevor Williams couldn't win one of Pittsburgh's open spots in the rotation coming out of spring, and when he got the opportunity to be a starter in May, things didn't flow right away.

They flowed pretty well Monday night.

Williams pitched one-hit ball over seven scoreless innings, and John Jaso smacked a pinch-hit, two-run homer as the Pittsburgh Pirates beat the Detroit Tigers 3-0 at PNC Park.

"Experience is the biggest confidence builder," Williams said. "If I'm getting the ball every fifth day, it's giving me confidence. When I see I can get guys without my greatest stuff, it gives me confidence that I can go to it when I don't have it that day."

George Kontos, in his Pittsburgh debut after being picked up off waivers Saturday, and Juan Nicasio each pitched a perfect inning in relief to complete the shutout. Nicasio earned his second save.

"Can't win if you don't score," Detroit manager Brad Ausmus said.

The Tigers' only hit was a leadoff single by James McCann in the third.

Williams (5-4) walked two, struck out five and threw a career-high 107 pitches. He was perfect through two innings and pitched to one batter over the minimum through six.

He was coming off two consecutive no-decisions in which he allowed a combined three earned runs. He has yielded more than three earned runs just once in his first nine starts at PNC Park.

Pittsburgh manager Clint Hurdle said Williams was building toward an outing like this, even if the right-hander wasn't perfect.

"He's had a number of performances where he hasn't had a run, low number of hits going into the sixth, seventh, eighth innings," Hurdle said. "To be able to finish it off, some of the indicator numbers weren't where you'd think they might have to be have this kind of outing. It was just old-fashioned pitching tonight. Old-fashioned really good pitching today.

"Extremely solid, solid, aggressive ballgame."

It was one that left Williams feeling pretty good about his overall game.

"I think I'm pitching more like myself," Williams said. "At the beginning of the year, I was getting away of who I was as a pitcher. When I was a reliever I was trying to throw it 95 (mph) every pitch. That's not the pitcher that got me to the major leagues.

"I got punched in the face early in the year starting like that. Had to take a step back. Maybe it's fastball location, it's changing speeds, going up and down. Luckily, we found that and recognized that. We've continued to build on it since May."

Jaso, batting for Williams, hit his eighth homer, third as a pinch hitter, in the seventh inning, giving Pittsburgh a cushion. The Pirates were riding a 1-0 lead since Francisco Cervelli's RBI double in the second.

Pittsburgh (55-57) won its second straight. Detroit (51-60) lost its third in a row.

Tigers starter Jordan Zimmermann (7-9) had a strong outing, just not as strong as Williams' performance. Zimmermann, attempting to win consecutive starts for the first time since late April, allowed three runs on five hits over seven innings with two strikeouts and three walks.

"It's unfortunate because (Zimmermann) pitched outstanding," Ausmus said. "He gave up a two-run homer to Jaso, but, really, he was holding them off. He couldn't hold them off forever."

With one out in the second, Gregory Polanco was hit by a pitch. Cervelli drove in Polanco with a full-count, two-out double to the right-center gap for a 1-0 lead.

"I was going after him no matter what," Zimmermann said of Cervelli, the No. 8 hitter. "I always want the pitcher leading off the next inning. Sometimes it burns you. If I get him out, I've got the pitcher leading off the next inning."

In the seventh, Cervelli walked with two outs and scored on Jaso's homer to right to make it 3-0.

"I made the pitches when I needed to, except for that last one to Jaso," Zimmermann said. "I think I went to the well one too many times with the curveball and I left it (in the) middle. If I throw it away where the other ones were, it would probably be a different result."

The pitch fooled Jaso, but he was able to adjust.

"I was looking for a heater," he said. "(The curveball) just happened to be up at my eyes.

"Just basically at the end hung that. It was either ball four or I'm hitting it somewhere. I know he wasn't trying to throw it for a strike probably ... but we're all human. We make mistakes. I don't mind that."

NOTES: Pittsburgh RHP George Kontos reported to the team and tossed a 1-2-3 inning. He was acquired Saturday off waivers from the San Francisco Giants. The Pirates cleared a roster spot by optioning RHP Dovydas Neverauskas to Triple-A Indianapolis. Neverauskas pitched a total of four scoreless innings in three relief appearances for Pittsburgh this month ... Pittsburgh OF Danny Ortiz cleared waivers and was outrighted to Indianapolis. ... Detroit 3B Jeimer Candelario was promoted from Triple-A Toledo while SS Jose Iglesias is on bereavement leave.