MIAMI -- Ivan Nova is proving to be a wise acquisition for the Pittsburgh Pirates.

Nova pitched a three-hit shutout with no walks to lead Pittsburgh to a 4-0 win over the Miami Marlins on Saturday night at Marlins Park.

Nova (3-2), who struck out seven and has allowed just one walk in 27 innings this season, lowered his ERA to 1.50.

"Again, no walks," Pirates manager Clint Hurdle said of Nova, the ace the franchise acquired from the New York Yankees on Aug. 1 and then signed to a three-year, $27 million contract extension in December. "He only had three three-ball counts.

"That is the perfect recipe for somebody to pitch well. He used all four of his pitches very well."

It was the third career shutout for Nova (3-2), who did it twice for the Yankees in 2013. He blanked the Baltimore Orioles on three hits and one walk and did the same to the San Francisco Giants on six hits and one free pass.

On Saturday, Nova allowed a double by Martin Prado and two singles. Pinch hitter Derek Dietrich nearly homered to lead off the ninth, but his shot to right was foul by a couple of feet. Dietrich then hit a fly ball to center that was caught on the warning track.

Nova, who threw a season-high 95 pitches, has eight career complete games, including two this season.

"Every time you start, you want to think that way," Nova said when asked about pitching complete games. "A lot of the times, it doesn't happen. But when it does, it feels amazing."

Marlins manager Don Mattingly said Nova was able to pitch to both sides of the plate.

"He gave us a lot of trouble with his sinker and some four-seamers," Mattingly said.

The Pirates (11-12) have won a season-best four games in a row and will try for a three-game sweep against the Marlins on Sunday. The Marlins have lost a season-worst four straight games.

Pittsburgh was led offensively by Gregory Polanco, who went 2-for-3 with a pair of doubles, one walk and one run scored. John Jaso added a homer, his first of the season, and two RBIs.

Marlins starter Dan Straily (1-2), who was coming off a 14-strikeout, no-walk performance in a road win against the San Diego Padres, was not nearly as sharp vs. Pittsburgh. He lasted 5 1/3 innings, allowing four hits, three walks and three runs, striking out five.

Straily pitched well through five innings. The only damage he allowed during that portion of the game occurred in the second inning, when the Pirates took a 1-0 lead on Polanco's leadoff double to left and Jordy Mercer's two-out RBI single to center.

But after getting the first out in the sixth, Straily fell apart. He allowed a single by Josh Bell and then three straight walks, including an RBI free pass to Francisco Cervelli, who overcame an 0-2 count.

Mattingly brought in reliever Brad Ziegler, who walked Jaso on a low 3-2 pitch to force in a run, giving the Pirates a 3-0 lead. Ziegler escaped more trouble when the next batter, Mercer, grounded into a double play.

Straily blamed some of his issues to the fact that he hadn't pitched since last Saturday, with the extended rest due to the team having a rain-out in Philadelphia.

"It felt a bit foreign being out there after a week off," Straily said. "I wouldn't say I lost command (in the sixth). I was trying to get them to offer at some pitches, and they never took."

The Pirates extended their lead to 4-0 in the ninth on Jaso's homer to right-center field. Not knowing for sure if the ball would clear the wall, Jaso sprinted hard to third before finally trotting home.

That was more than enough offense for Pittsburgh, and it was Miami's first shutout loss of the season, which only adds to the Marlins' frustrations.

"We haven't been playing well," Marlins center fielder Christian Yelich said. "(Nova) did a great job, and we didn't."

NOTES: Pirates 3B David Freese (hamstring) was placed on the 10-day disabled list retroactive to April 25. His roster spot was taken by OF Danny Ortiz, who made his major-league debut as a defensive replacement in the seventh inning. Ortiz was recalled from Triple-A Indianapolis. ... Marlins RHP Jose Urena set a Marlins record for a reliever by allowing 12 hits in Friday night's game. ... In three road starts this season, Pirates RHP Jameson Taillon is 2-0 and has allowed just one earned run in 19 innings. ... Pirates utility INF Adam Frazier (left hamstring) hasn't resumed baseball activities since landing on the disabled list on Monday. ... The pitching matchup for Sunday's series finale features Marlins RHP Tom Koehler (1-1, 5.14 ERA) vs. Pirates RHP Chad Kuhl (1-2, 6.63).