PITTSBURGH -- On Friday in Milwaukee, Arizona Diamondbacks catcher Chris Iannetta hit a solo home run with two outs in the top of the ninth inning to tie the game against the Brewers. The D-backs won in the 10th.

On Monday at PNC Park, Iannetta did it again, this time belting a two-run homer off Pittsburgh Pirates closer Tony Watson with two outs in the top of the ninth to tie the game at 3.

However, shortly thereafter in the bottom of the inning, Andrew McCutchen went off the script.

Struggling through a difficult season, which followed a difficult 2016 season and even a tough offseason, the Pirates' beleaguered star sent Archie Bradley's fastball to the opposite field and into the right field seats to give his team a 4-3 victory.

McCutchen, who was leading off the inning, blasted Bradley's 1-1 pitch.

"With a guy like Bradley, he's a guy that has good stuff," said McCutchen, who came in hitting .213 and exited with the sixth game-winning homer of his career. "His fastball can jump on you at times.

"For me to be in a spot and a position where I get a fastball out over the plate and I can drive it out to right field, that shows that I'm in a good spot, because a week ago, I probably wouldn't have been able to do that."

Bradley (1-1) knew instantly he made a mistake.

"Just right down the middle," he said. "He's a great hitter, he's been doing it for a long time. Tie ballgame, that type of situation, you just have to make a better pitch."

Iannetta said manager Torey Lovullo mentioned in the dugout he wanted "someone fast" to pinch-hit. Iannetta is not fast. He said he told Lovullo, "How about jogging?"

Iannetta added, "I was just joking."

Lovullo didn't think so.

"I think he loves those moments," Lovullo said.

The Pirates broke open a 1-1 game in the seventh on Chris Stewart's two-run double before Iannetta tied it up.

In the sixth inning, Pirates right fielder Gregory Polanco sprained his right ankle after he crashed into the fence while chasing a foul ball that ended up in the seats. X-rays on the ankle were negative.

Stewart also departed after sliding into third base on his triple. He injured his left calf or hamstring, according to the club, but it is not believed to be serious.

In his best start of the season, Pirates right-hander Trevor Williams, who carried a 5.93 ERA coming in, pitched six innings. He gave up only one run, on Yasmany Thomas' RBI single in the first inning. Williams yielded four hits, struck out three and walked none.

Randall Delgado, starting his second game for Arizona after spending most of the season in the bullpen, gave up one run on five hits in 5 2/3 innings. He struck out eight and walked none.

Delgado gave up singles to Jordy Mercer and Alen Hanson his first time through the batting order but faced the minimum nine hitters after catcher Jeff Mathis threw both out at second trying to steal.

Mercer tripled with one out in the fourth and scored on Josh Bell's sacrifice fly to make it 1-1.

Watson (4-1) got the win despite giving up two runs in his lone inning.

NOTES: The eight strikeouts for Arizona RHP Randall Delgado were his high since he struck out nine on July 3, 2013, against the New York Mets. ... With three hits, Pirates SS Jordy Mercer is 15-for-31 (.484) in his past eight games. ... Pirates C Chris Stewart's triple was the second of his 10-year major league career. He hit his first on April 23.