Young's 27th homer of the season was a solo shot in the bottom of the first. His 28th homer was a three-run shot in the second.
Jeff Cirillo drove in Arizona’s other run with a single in the second. Like Young, Jeff Salazar had two hits for the NL West-leading Diamondbacks, who won twice in the three-game series.
The winner was Edgar Gonzalez (6-2).
Closer Jose Valverde recorded his 40th save of the season.
Aramis Ramirez also had one RBI, and a run scored on Scott Drew’s first-inning throwing error for the Cubs, who have lost three of four.
The losing pitcher was Cubs starter Jason Marquis (10-8).