CHICAGO (Interstat) — Matt Chapman drove in eight runs with two home runs, including a grand slam, and Casey Schmitt also homered twice as the San Francisco Giants routed the Chicago Cubs 18-3 on Friday afternoon at Wrigley Field.

The Giants pounded out 19 hits and hit seven home runs, scoring in five innings. San Francisco improved to 26-38, while Chicago dropped to 33-31.

The game turned decisively in the fourth inning. After the Giants had taken a 2-0 lead in the first on Willy Adames’ two-run homer, they blew the game open with a six-run fourth. Luis Arraez led off with a single, Adames walked and after Jung Hoo Lee struck out, Bryce Eldridge singled to load the bases. Chapman then crushed a 1-0 pitch from Edward Cabrera over the center-field fence for his third home run of the season, scoring all three runners. Daniel Susac grounded out, Drew Gilbert singled and Schmitt followed with a two-run homer to left-center, his 14th. Rafael Devers singled before Arraez grounded out.

Cabrera was charged with eight runs on seven hits in three-plus innings, walking two and striking out three. He fell to 3-3.

The Giants added a run in the fifth on a sacrifice fly by Chapman, scoring Adames, who had walked and moved to third on a double by Lee.

Then in the sixth, the Giants erupted for seven runs. Jonah Cox, pinch-hitting, singled off reliever Ethan Roberts. Schmitt singled, and Devers doubled to drive in Cox and send Schmitt to third. Arraez sacrificed Schmitt home with a fly ball to center. Adames then homered to left-center, his 11th, scoring Devers. Lee was hit by a pitch, Eldridge singled and Chapman hit his second homer of the game, a three-run shot to left field, scoring Lee and Eldridge. Susac struck out, but Cox singled again, and Schmitt singled before Devers struck out.

By that point, the Giants led 16-0.

The Cubs avoided a shutout with a run in the sixth. Seiya Suzuki walked, Pedro Ramírez singled and Carson Kelly singled to score Suzuki. A double play ended the threat.

In the eighth, Suzuki homered to left-center, his ninth, and Miguel Amaya doubled in Ramírez to make it 16-3.

San Francisco answered with two more in the ninth. Cox homered to center, his first, and Schmitt followed with his second homer of the game, a solo shot to left-center, his 15th.

Robbie Ray started for the Giants and earned the win, improving to 4-6. He allowed one run on three hits over six innings, striking out four and walking four. Dylan Smith pitched a perfect eighth with two strikeouts. Carson Seymour worked three innings of relief, allowing three runs on six hits with one strikeout.

For the Cubs, Suzuki homered and Kelly drove in a run. Ramírez had two hits and scored twice. Michael Busch and Michael Conforto each singled. Nico Hoerner grounded out twice and flew out. Dansby Swanson reached on a force out but otherwise was retired. The Cubs left six runners on base and grounded into two double plays.

The Giants’ offense was balanced. Schmitt went 4 for 6 with two home runs and three RBIs. Cox went 3 for 3 with a home run and an RBI. Devers had two hits and an RBI. Adames drove in three runs with two hits, including two homers. Arraez doubled and singled. Eldridge had two hits. Gilbert singled twice. Chapman’s eight RBIs were a career high. Victor Bericoto went 0 for 2, Buddy Kennedy 0 for 1. Daniel Susac struck out three times. Lee finished 1 for 4 with a double and a hit by pitch.

The Giants made two sacrifice flies, both by Chapman. The Cubs turned a force out in the fourth but could not turn a double play.

Attendance was 39,060, and the game lasted 2 hours, 53 minutes.

The victory gave the Giants their second straight win after a 12-9 decision at Milwaukee on Thursday. They had lost four of five before that. The Cubs had won two of their previous three but fell to 1-2 on their homestand.

Interstat’s game simulator had projected a final score of Chicago 4, San Francisco 3, and the Cubs were installed as a pregame favorite with a spread of minus-1.5. Interstat’s ELO system gave Chicago a 60.80 percent probability to win. The total score of 21 went under the over/under line of 11.5.

The two teams meet again Saturday afternoon at Wrigley Field, with the Giants seeking a series win.