PITTSBURGH (Interstat) — Ryan O’Hearn hit a grand slam in the third inning and rookie Shawn Ross added his first major league homer as the Pittsburgh Pirates held off a late Chicago Cubs rally to win 8-7 on Sunday afternoon at PNC Park.

The victory before 32,921 fans in a game that lasted 2 hours, 26 minutes allowed Pittsburgh to salvage the finale of a three-game series after the Cubs won the first two by a combined 14-2. The Pirates improved to 54-52, while the Cubs fell to 59-46.

Braxton Ashcraft earned the win for Pittsburgh, his 10th against four losses, by allowing four earned runs on seven hits over six innings with five strikeouts and one walk. Mason Montgomery worked a shaky ninth inning for his second save, surrendering two earned runs on two hits with two strikeouts.

Jameson Taillon took the loss for Chicago, his sixth against two wins.

Chicago struck first in the second inning. Michael Conforto walked and moved to second on a Pedro Ramírez single. Dansby Swanson then laced a ground-ball single to left field, scoring Conforto and putting Ramírez at third. But Ashcraft escaped further damage by striking out Pete Crow-Armstrong.

The lead did not last. In the bottom of the second, Esmerlyn Valdez launched a 14th home run of the season to left-center field to tie the game. After Ryan O’Hearn walked and Nick Gonzales flied out, Jacob Gonzalez grounded out but moved O’Hearn to second. Shawn Ross then crushed his first career homer to left field, scoring O’Hearn and giving Pittsburgh a 3-1 lead.

The Pirates blew the game open in the third. Brandon Lowe singled and Bryan Reynolds doubled, putting runners at second and third. Valdez walked to load the bases. O’Hearn then drove a 1-0 pitch over the center-field wall for a grand slam, his 17th homer of the season, extending the lead to 7-1.

Chicago chipped away in the fourth. Nico Hoerner singled and Michael Conforto doubled, putting two in scoring position. Carson Kelly grounded out to third, allowing Hoerner to score. Pedro Ramírez singled to center, plating Conforto. After Swanson grounded out, Crow-Armstrong tripled to center field, scoring Ramírez and cutting the deficit to 7-4.

Pittsburgh answered in the fifth. Brandon Lowe led off with a double, moved to third on a groundout by Bryan Reynolds and scored on a single to right by Valdez, making it 8-4.

The Cubs mounted a comeback in the eighth. Michael Busch doubled and Ian Happ singled, putting runners at the corners. Hoerner lined a single to left, scoring Busch and moving Happ to second. But reliever Carmen Mlodzinski entered and struck out two batters before getting a groundout to end the threat with the score 8-5.

In the ninth, the Cubs made it close. Swanson singled to right off Montgomery. After Crow-Armstrong struck out, Seiya Suzuki homered to left field, his 18th of the season, driving in Swanson and pulling Chicago within one. But Montgomery retired Michael Busch on a groundout and struck out Ian Happ to end the game.

Key performances for Pittsburgh included Brandon Lowe going 3-for-4 with a double and two runs scored. Nick Gonzales had two hits in four at-bats. Valdez finished 2-for-3 with a home run, two RBIs and two runs scored. O’Hearn drove in four runs.

For the Cubs, Suzuki hit his 18th homer and drove in two runs. Hoerner had two hits. Busch doubled and scored twice.

The most important sequence of the game occurred in the bottom of the third inning. With the Pirates already leading 3-1, they loaded the bases on a single, a double and a walk. O’Hearn then crushed the grand slam, turning a two-run contest into a six-run cushion that proved insurmountable even as Chicago scored three runs over the final two frames.

Carmen Mlodzinski provided critical relief for Pittsburgh, working two innings allowing one earned run on three hits with two strikeouts.

Pittsburgh’s victory snapped a two-game losing streak in the series. The Cubs had won the previous two meetings by scores of 11-0 and 3-2 in 10 innings.

Chicago now heads to St. Louis for a four-game series beginning Monday. Pittsburgh opens a three-game home set against Arizona on Monday.

The interstat game simulator had projected a final score of Chicago Cubs 6, Pittsburgh Pirates 5. Interstat’s ELO system gave the Cubs a 52.60 percent probability to win. Pittsburgh was installed as a pregame favorite with a spread of minus-1.5. The total score of 15 went under the over-under line of 8.5.