PHOENIX — Pittsburgh’s slow start to the season is quickly fading into the rearview mirror.

The Pirates can thank their starting pitchers for the turnaround.

Francisco Liriano pitched effectively into the seventh inning in a combined three-hitter and the Pittsburgh Pirates completed their first sweep in Arizona with an 8-0 win over the Diamondbacks on Sunday.

“We’re playing better baseball and it continues to start with our mound work,” Pirates manager Clint Hurdle said.

Gerrit Cole and A.J. Burnett got the Pirates rolling in the series with quality starts the first two games.

Liriano (1-1) had trouble with fastball command in his 200th career start and walked six. He offset the walks with seven strikeouts and allowed two hits in 6 1-3 innings, giving him wins against 29 of the 30 teams in the majors.

The Pirates gave him some rare support, too.

Pedro Alvarez hit a two-run single off Jeremy Hellickson (1-3) in the first inning and Neil Walker added a two-run double off the right-hander in the fifth. Gregory Polanco had three of Pittsburgh’s 14 hits and scored three runs. Walker also had three hits, finishing the series 7 for 12.

Pittsburgh has won five straight and eight of 10.

“We’re in a good place right now,” said Liriano, who has never faced Miami. “We keep playing hard, taking it one game at a time, and pretty comfortable right now.”

Liriano has been sharp dating to the end of last season, allowing three earned runs or less in 10 straight starts.

He hasn’t had much luck turning those quality starts into wins this season, though, losing to Detroit on April 15 after the Pirates were shut out and getting two no-decisions.

The left-hander had another good outing, keeping Arizona’s hitters off-balance with his slow breaking balls.

Liriano was lifted after walking two with one out in the seventh. Jared Hughes ended the threat with a quick inning-ending double play.

“We knew we had to get the ball up and we kept swing at balls in the dirt,” Diamondbacks manager Chip Hale said of facing Liriano.” Execution. You can have the best game plan in the world, if you cannot execute it, you are not going to do well.”

The Pirates gave him a cushion right out of the gate against Hellickson.

The Arizona right-hander has struggled in the first inning this season, allowing four of his nine runs heading into Sunday’s game in the opening frame.

The right-hander stumbled through the first again, loading the bases with the first three batters he faced to set up Alvarez’s two-run single.

Hellickson ran into trouble again in the fifth inning, when Walker hit a two-run double to put the Pirates up 4-0, giving Pittsburgh eight straight runs with two outs to start the series.