PITTSBURGH -- A two-run homer by Pavin Smith in the seventh helped lead the D-backs to a 4-3 come-from-behind win over the Pirates on Saturday afternoon at PNC Park.

Here are some key moments that led to the victory:

Brandon Pfaadt kept the D-backs in the game
The rookie right-hander, making his fourth big league start, pitched out of a first-and-second jam in the first inning and worked around a leadoff single in the fourth.

The only damage against him came in the third, when he allowed a leadoff single and issued a pair of walks, including one with two outs.

That set the stage for Ke’Bryan Hayes’ three-run triple off the wall in right that gave Pirates ace Mitch Keller a 3-1 lead.

Pfaadt -- ranked by MLB Pipeline as the D-backs' No. 3 prospect -- had retired six straight hitters when D-backs manager Torey Lovullo went to the bullpen with one out in the sixth.

“He threw the ball really, really good,” Lovullo said. “I just elected to take him out of the game because I felt like the tide was turning and I just wanted to keep momentum on our side. As far as we're concerned, he landed pitches, kept us in the game and gave us a chance to win. It was a quality start for me.”

It was an eventful third inning defensively for Smith
The Hayes at-bat in the third took a lot out of Smith.

On the first pitch, Hayes lifted a fly down the line in right. Smith, who was playing a little over towards the gap in center, tried to make a diving play in foul territory and just came up short, ending up hitting his head and neck on the wall.

They shifted him a little closer to straightway right after that foul and Hayes then hit a 1-1 pitch back towards the spot Smith was originally at, and his jump at the wall came up just short as the Pirates runners circled the bases.

“It seemed like I missed by a combined three inches on both of them,” Smith said. “They moved me over and in and then he hit it where I was gonna be, so that's just baseball sometimes. You can’t exactly predict what's going to happen.”

The D-backs wore down Keller
Keller allowed a solo homer to Ketel Marte in the first and then retired 16 straight D-backs hitters before hitting Josh Rojas with a pitch in the top of the sixth inning.

Marte then beat out a tapper to third to reach base. Both he and Rojas stole bases to put them at second and third, and Corbin Carroll beat out an infield grounder up the middle to score Rojas, pulling the D-backs to within 3-2. But more importantly, it prompted Pirates manager Derek Shelton to take his ace out following the inning after having thrown just 84 pitches.

“In the sixth inning there he kind of lost his delivery a little bit,” Shelton said. “We saw the pitches start to not have the same action. As well as he’s pitched over the last two starts -- and even today -- he hadn’t been in the stretch. Once he got to the stretch, he kind of lost where his arm slot was.”

The game shifted when the Pittsburgh bullpen got involved
Robert Stephenson came on to pitch for the Pirates, and he allowed a leadoff single to Lourdes Gurriel Jr. before Smith followed with his clutch homer, his third of the season. The go-ahead two-run blast was the third of Smith’s career in the seventh inning or later.

“I think we did a good job of getting Keller out after six,” Smith said. “Grinded a couple of runs off him. It didn’t look pretty [in the sixth] but getting the run off him and being able to get into that bullpen was huge.”

Smith got ahead 3-0 against Stephenson before taking a called strike. The next pitch was a 96 mph fastball that he hit into the seats in right-center.

“I just tried to keep things simple,” Smith said. “Once I got 3-1, I took my chance on getting a fastball, tried to see it and put a good swing on it.”