CHICAGO (Interstat) — Michael Busch had two hits and two RBI, and Colin Rea pitched into the sixth inning as the Chicago Cubs held off the Arizona Diamondbacks 6-5 on a sunny afternoon at Wrigley Field.

The Cubs built a 6-1 lead with three runs in the first and three more in the fourth, then survived a four-run Arizona rally in the sixth that cut the margin to one. Jacob Webb worked two scoreless innings for his first save of the season.

Rea (4-1) allowed two runs on eight hits over 5 1/3 innings, striking out six and walking two. He left after allowing a leadoff single in the sixth, but the Diamondbacks erupted against the bullpen before Webb shut the door.

Zac Gallen (1-2) took the loss for Arizona, giving up six runs on seven hits in four innings. He walked four and struck out two.

The Cubs struck first against Gallen in the bottom of the first. Nico Hoerner led off with a double, and after a walk to Moisés Ballesteros and a force out, Ian Happ walked to load the bases. Busch singled to left, scoring Hoerner and Alex Bregman, and Carson Kelly followed with an RBI single to make it 3-0.

Arizona got one back in the third. Jorge Barrosa doubled, moved to third on a groundout and scored on Ildemaro Vargas’ single.

Chicago answered in the fourth. Carson Kelly singled and Pete Crow-Armstrong singled to put runners at the corners. Dansby Swanson lined a single to left, scoring Kelly. After a strikeout, Ballesteros flied out, but Bregman doubled to left, scoring Swanson for a 6-1 lead.

The Diamondbacks mounted their comeback in the sixth. Jose Fernandez led off with a single off Rea. After a strikeout, Tim Tawa walked. Barrosa then bunted for a double down the third-base line, scoring Fernandez and sending Tawa to third. Geraldo Perdomo followed with a three-run homer to left, cutting the deficit to 6-5. Vargas added a single, but reliever Phil Maton struck out Corbin Carroll and Adrian Del Castillo to end the inning.

From there, the Cubs bullpen took over. Maton worked a scoreless sixth, and Webb pitched the seventh and eighth, striking out three and allowing no baserunners. In the ninth, Webb walked Vargas but then struck out Carroll, got Ketel Marte on a force out and struck out Gabriel Moreno to end the game.

Vargas had four hits in four at-bats for Arizona, including a single and an RBI. Perdomo drove in three runs with a home run and a single. Barrosa doubled twice and drove in a run.

For Chicago, Busch doubled and singled, scoring two. Bregman doubled and drove in a run. Hoerner left the game in the second inning because of neck tightness after his leadoff double.

The attendance was 31,083, and the game lasted 2 hours, 52 minutes.

The Cubs improved to 20-12 with their third straight victory, while Arizona fell to 16-15. The Diamondbacks had lost two of three in Milwaukee before arriving in Chicago.

The series continues Saturday and Sunday at Wrigley Field, then Arizona returns home to face Pittsburgh, while Chicago hosts Cincinnati.

Interstat’s game simulator projected a final score of Chicago Cubs 7, Arizona Diamondbacks 5. Interstat’s ELO system gave the Cubs a 59.80 percent probability to win. Chicago was installed as a pregame favorite with a spread of minus 1.5. The total score of 11 went under the over-under line of 7.