HOUSTON -- One big part of the A's starting rotation took a step toward returning to action Tuesday. One big piece of the bullpen still has a long road ahead.

Rich Harden threw off a mound for the first time in almost two months and looked sharp, according to manager Bob Geren and pitching coach Curt Young. The right-hander, who has been sidelined with a strained right shoulder since leaving an April 15 start, hit the low 90s on the radar gun during a 30-pitch session, which featured strictly fastballs.

"It takes time to get back into it," said Harden, who had been limited to flat-ground throwing until Tuesday. "But it felt really good. My command was good."

Though a possible plan has Harden pitching out of the A's bullpen rather than go on a rehab assignment to build up arm strength, Young said Tuesday that Harden could make an appearance for Single-A Stockton or pitch in a simulated game if he felt he needed it to prepare for major-league hitters.

Harden is on an every-other-day throwing program right now and is likely to try throwing some changeups Thursday.

"We haven't sat down and said (what the plan) is," Young said. "He hasn't faced hitters in two months."

It's unclear how a minor-league stint might impact whether Harden temporarily goes to the bullpen when he returns to the A's. But the overall health of the relief corps won't be a factor, even as assistant general manager David Forst said closer Huston Street had a setback in his recovery from a right elbow injury. Street threw Friday and was scheduled to throw again Sunday, but the plan was scrapped. He's been on the disabled list since May 13 with an irritated ulnar nerve.

"Huston was a little sore the last time he threw," Forst said. "He's going to take some more time before he tries it again."

There's also no sign of when setup man Justin Duchscherer might start throwing again. He's been on the DL since May 15 with complications from his arthritic right hip.

Forst, though, said injuries in the bullpen won't influence whether Harden pitches in relief.

"With a guy like Rich, we don't want to tailor his progression based on other guys," Forst said, adding that whether Harden starts or relieves upon his return will depend on "his comfort level."

Forst reiterated the organization does not plan to convert Harden to a full-time reliever.

Short hops

Designated hitter Mike Piazza hit in a cage off live pitching for the first time since suffering a sprained right shoulder May 2. He joked that he felt "like a 6 year old" early in the session as he shakes off rust. "I'll hit (today). Then I'll get to regular batting practice. Then we'll see what the rehab situation is." Geren has said it's doubtful Piazza will return before the All-Star break July 9-11. ... Outfielder Travis Buck said his jammed right thumb was feeling better but he was not in Tuesday's lineup against the Houston Astros. ... Catcher Jason Kendall showed up for Tuesday's game with a shaved head, but his batting helmet rattled around as he tried it on before batting practice. He then informed equipment manager Steve Vucinich that he needed some more padding. "I have to change everything," Kendall said. ... Former A's reliever Jay Witasick signed with the Tampa Bay Devil Rays. ... The A's sent Single-A left-hander Ben Jukich to the Cincinnati Reds to complete the deal for outfielder Chris Denorfia. The Reds previously received right-hander Marcus McBeth.

-- Joe Stiglich