Pittsburgh Pirates pitcher Andrew Heaney throws a pitch against the Chicago Cubs during the fifth inning of Sunday’s baseball game at Wrigley Field in Chicago. Associated Press

CHICAGO — Dansby Swanson hit a tiebreaking sacrifice fly in the eighth inning, and the Chicago Cubs beat the Pittsburgh Pirates 4-3 Sunday in the rubber game of the weekend series.

Pete Crow-Armstrong and Ian Happ each had two hits for Chicago, which had dropped four of five before a 3-1 victory Saturday.

Next up is a big five-game series against major league-leading Milwaukee, beginning with a split doubleheader Monday at Wrigley Field. The Cubs are eight games back of the Brewers in the National League Central.

Chicago had runners on second and third with one out in the eighth when Isaac Mattson (3-2) issued an intentional walk to Nico Hoerner. Swanson followed with a flyball to right, driving in Carson Kelly.

Caleb Thielbar (3-3) got one out for the win, and Andrew Kittredge pitched a 1-2-3 ninth for his first save.

Pittsburgh trailed 2-1 before Joey Bart lined a two-run double into the corner in left in the sixth. Ronny Simon's two-out single put runners on the corners, but Ben Brown escaped the jam when Spencer Horwitz bounced to second.

Chicago tied it at 3 on Carson Kelly's bloop single in the bottom half, driving in Seiya Suzuki. The Cubs had the bases loaded with two down, but Swanson flied to right for the final out of the inning.

The Pirates wasted a prime scoring opportunity in the eighth. Batting with a runner on third and one out, Bart struck out swinging against Brown. Isiah Kiner-Falefa then walked before Thielbar fanned Ronny Simon for the final out of the inning.

The Pirates went 3 for 13 with runners in scoring position and left 10 on base.

Pirates RHP Paul Skenes (7-9, 2.13 ERA) starts Monday night in the opener of a three-game series against Toronto. RHP Kevin Gausman (8-9, 3.79 ERA) goes for the American League East leaders.