CHICAGO -- Forget about the big matchup between Big Z and the Big Unit.
Johnson, who had offseason back surgery, is 2-1 with a 5.06 ERA this season but has a 12-0 career record against the Cubs. Zambrano (5-1, 1.80 ERA) is off to one of his best starts but has struggled in four outings against Arizona, going 1-2 with a 4.88 ERA.
Zambrano is scheduled to pitch Monday against San Diego, but the rotation is unclear beyond that.
The Diamondbacks also held out second baseman Orlando Hudson, who missed his sixth straight game with a strained right hamstring.