Rookie Owen Caissie hit his first major league home run and drove in three runs in Game 1 of a day-night doubleheader on Tuesday, helping the Chicago Cubs post a 6-4 victory over the visiting Milwaukee Brewers.

With Milwaukee trailing by two runs in the ninth, Sal Frelick worked a one-out walk before Caleb Durbin singled against Cubs closer Daniel Palencia. William Contreras then grounded into a game-ending double play as Palencia picked up his 17th save of the season.

Matthew Boyd (12-6) threw 5 1/3 innings, allowing four runs on six hits while striking out three and walking three for Chicago, which won its third game in four tries.

Chad Patrick (3-8) allowed five runs (three earned) on five hits in five innings, striking out four and walking two for the Brewers, who have dropped two of three since their franchise single-season record 14-game winning streak. Frelick went 2-for-4 with two RBIs for Milwaukee, which holds an eight-game advantage over the Cubs atop the National League Central.

After Chicago's Ian Happ doubled and advanced to third on a wild pitch in the first inning, Seiya Suzuki walked before Happ was tagged out at home on Pete Crow-Armstrong's grounder to third base. Following Milwaukee first baseman Andrew Vaughn's throwing error, Caissie -- who entered the game 1-for-8 since making his major league debut on Thursday -- drove in a pair of runs on a single to right.

In the third, Suzuki walked with one out and Crow-Armstrong doubled before Willi Castro belted a three-run homer -- his 11th of the season and first since being traded from Minnesota -- to give the Cubs a 5-0 lead.

The Brewers got a run back in the fourth on Christian Yelich's 26th homer of the year. Frelick pulled Milwaukee within three with a run-scoring single in the fifth.

After Vaughn began the sixth with a double, Brice Turang drove him in with a one-out single, chasing Boyd from the game. Reliever Brad Keller entered and struck out Blake Perkins, then walked Joey Ortiz and allowing Frelick's RBI single, cutting the Brewers' deficit to 5-4.

Shelby Miller replaced Patrick in the bottom of the sixth, and he allowed Caissie's one-out home run to left-center field.