ANAHEIM, Calif. — Justin Duchscherer came off the disabled list, then was scratched from his scheduled start. Now, the oft-injured pitcher isn't sure when his aching hip might allow him to get back on the mound.

A two-time All-Star, Duchscherer was activated from the 15-day DL on Saturday and lined up to start against the Los Angeles Angels. But the A's made a last-minute change and sent Tyson Ross to the mound for his first major league start due to a recurrence of the inflammation in Duchscherer's troublesome left hip that has sidelined him since his most recent outing April 29.

"For my warmup, I usually run to center field and back just to jog, and I felt something in my hip," said Duchscherer, who has had two operations on his other hip. "I came in and told Curtis (pitching coach Curt Young) that something didn't feel quite right. I let him know early just in case he needed to get somebody going.

"As I was throwing (on flat ground), my hip felt OK, but it just got kind of achy," he added. "Then when I was in the bullpen, I just couldn't find a way to land without having pain. I started throwing from the stretch, and then I told Curt: `I can't throw like this."'

A's manager Bob Geren said after Saturday night's 12-3 loss it was "probable" that Duchscherer would have to go on the DL for the seventh time in his career.

"If I have to have surgery, I'm done for the year," Duchscherer said. "That's obviously not an option I want to explore unless it's absolutely necessary. I don't want to do it. It's very mentally draining."

Duchscherer dismissed the idea that his mechanics have led to his hip problems.

"I've talked to both my pitching coaches, Curt Young and Ron Romanick, and they said I have some of the best mechanics they've ever seen," the right-hander said. "I never asked the question, `If that's true, then why do I get hurt?' But I think more than anything, it's genetic. I mean, I have a little bit of a genetical issue with the size of the head of my femur.

"From what I was told by the doctor, over years and years of grinding and pounding, the cartilage gets worn away in the hips — which is something I can't really control," Duchscherer added. "It's very frustrating because I feel like I'm a really good pitcher, and I don't need to be a power pitcher to pitch at this level. But my body's not cooperating."

Duchscherer lasted just 3 1-3 innings in his last outing, giving up four runs in a 6-3 loss at Toronto. He missed last season after he underwent arthroscopic right elbow surgery on March 31 and later was treated for clinical depression.

"The first option would be to go see a doctor and re-evaluate him. And whatever they recommend from there would be up to who he sees," Geren said.

In other news, Oakland promoted slugger Jack Cust from Triple-A Sacramento.

Cust batted .273 with 19 RBIs in 33 games for Sacramento and hit four homers, all of them in consecutive games. The outfielder-designated hitter was with the Athletics in spring training before they designated him for assignment April 3. He then cleared waivers and was sent outright to Sacramento.

Cust led the A's with 25 homers last year, but also led the AL in strikeouts for the third consecutive season.

"We were at three position players, and we thought he could help," Geren said. "He was off to a nice start down there and he's swinging the bat well. He just wanted to get his swing and rhythm back, and his eye was outstanding. He had 30-something walks already, so he was swinging at strikes."

Cust became a free agent at the end of last season after the A's declined to offer him a contract for this year, but they eventually re-signed him to a $2.65 million, one-year deal, including performance bonuses that would allow him to make an additional $350,000 if he had 600 plate appearances in 2010.

To make room on the roster for Duchscherer and Cust, Oakland optioned right-hander Henry Rodriguez to Sacramento and designated right-hander Edwar Ramirez for assignment.