TUCSON - As in almost every spring in his storied career, Randy Johnson’s next start will be on Opening Day. This time it will not be with the Diamondbacks, however.

Johnson will open the regular season on the disabled list, organizational sources said Wednesday, and will make his next start in the Triple-A Tucson Sidewinders’ season opener Wednesday at Tucson Electric Park.

Johnson is likely to make one more start with the Sidewinders during their season-opening homestand before possibly joining the D-Backs for the final game of their first homestand April 13.

Asked if he had a target date for reaching the majors, Johnson said: “Whenever I am ready. I’ll make one more (start) right now and see how I feel.”

Johnson has pitched only 11 1-3 innings this spring, about half the workload of the other D-Backs’ starters, including his 3 1-3 innings against the White Sox in a minor league game Wednesday.

Johnson threw 75 pitches, giving up nine hits and five runs while striking out five and walking two.

He threw a dozen or so changeups, saying he wanted to determine which off-speed pitch — a changeup or a split-finger fastball — will best suit him this season.

White Sox prospect Thomas Collaro, who hit 23 home runs in the minor leagues last season, homered on a changeup.

Johnson later fell behind former major leaguer Jeff Liefer 2-0 but threw two consecutive changeups, getting Liefer to foul out on the second one.

“I like goofing around. I like tinkering with pitches. I’m just trying to re-invent the wheel,” Johnson said.

“I might be able to take more velocity off” with the changeup. “If I’m topping out at 93 (mph) and I could throw a changeup at 72 miles an hour, that’s a 21-mile an hour variance, which is what you want.”

PITCHING STAFF DECISIONS

Yusmeiro Petit is under strong consideration for the roster spot available when Johnson goes on the disabled list.

That means the D-Backs may risk losing either Dustin Nippert or Brandon Medders on waivers this weekend.

While that is a gamble, they almost certainly will have to expose one to waivers when Johnson returns in about two weeks, anyway.

Petit, who is scheduled to pitch today, has a 2.92 ERA in six spring appearances, all in relief. Medders has a 4.91 ERA in eight spring games. Nippert’s ERA is 14.40 in eight games.

SHORT HOPS

Pitcher Juan Gutierrez was optioned to the minor league camp Wednesday, and he is expected to open the season in the Sidewinders’ rotation. Gutierrez hit 94 mph this spring and showed “electric stuff,” Melvin said, although he needs to work on holding runners and throwing his curve ball out of the stretch. …

Alex Romero had three more hits Wednesday, raising his batting average to .352. He threw Troy Tulowitzki out at home plate from left field and continues to be a viable contender for the final position player spot. “He is making a noise,” Melvin said. Although finding a 40-man roster spot for minor league invitee Trot Nixon does not appear to be a problem, the D-Backs would save a about $350,000 if they kept Romero over Nixon. Romero has not played first base, and Nixon has, but Chris Burke also could play there while Chad Tracy recovers.