OAKLAND -- The A's opened the second half of the season by making an all-too-familiar roster move, placing righty Rich Harden on the 15-day disabled list, retroactive to July 8, with a strained right shoulder on Thursday morning.

Harden, who was on the DL from April 16-June 21 with the same injury, made three relief appearances without allowing a run in four innings before returning to Oakland's rotation last Saturday against Seattle. After allowing four runs over 2 2/3 innings and being lifted from the game, he noted a return of the pain and tightness that had shelved him in the first place.

The move to place him on the DL was not unexpected. Harden had an appointment with noted arm specialist Dr. Lewis Yocum in Los Angeles on Monday, and while an MRI exam revealed no additional structural damage, Yocum recommended at least two weeks of rest before Harden take another crack at rehab.

"It's obviously a blow for the club, but we've managed to do a pretty good job of staying afloat without him for most of the first half," said general manager Billy Beane, whose club went into the All-Star break at 44-44, despite having used the DL 16 times in three months.

"But first and foremost, you really feel for Rich."

Harden, who is 1-2 with a 2.45 ERA in seven games (four starts) this year, has now been on the DL five times in his short career. He also had two stints last year and one in 2005. He has appeared in just 38 games -- 32 starts -- since the beginning of the 2005 season and is 15-7 with a 2.92 ERA over that span.

"I'm happy the MRI didn't show anything serious or any structural damage," Harden told the San Francisco Chronicle on Wednesday. "I wanted to make sure I didn't hurt anything else. Basically, it's the same impingement. I'll rest a little bit, do some rehab outings and hopefully be able to help out the team and be part of that pitching staff that has done so well this year.

"Right now, the most important thing is to make sure I'm healthy for the stretch run."

Despite Harden's limited availability, and injuries to projected No. 3 starter Esteban Loaiza (bulging disc, knee surgery) and top relievers Huston Street (elbow), Justin Duchscherer (hip) and Kiko Calero (shoulder/biceps), the A's managed to lead the American League in ERA (3.68) in the first half.

Also Thursday, Oakland placed infielder Donnie Murphy on the bereavement list, recalled infielder J.J. Furmaniak from Triple-A Sacramento, and selected righty Andrew Brown from Sacramento.

To clear a spot for Brown on the 40-man roster, the A's transferred Duchscherer, who will miss the rest of the season after surgery on his arthritic hip, to the 60-day disabled list.

Brown, 26, was acquired by the A's from San Diego for Milton Bradley on June 29 and was assigned to Sacramento, where he picked up four saves in five games while posting a 3.60 ERA. The 26-year old Brown made his Major League debut with Cleveland last year and posted a 3.60 ERA in nine relief appearances.

Furmaniak joins the A's for the second time this year; he went 0-for-1 in one game during his first stint, June 16-20. He was batting .277 with 13 home runs and 44 RBIs in 83 games with Sacramento, including .286 with a pair of four-hit games following his option. Furmaniak has appeared in 42 games at shortstop, 18 at third base, 15 in left field, eight at second base and one in right field for the River Cats.

The A's have now used the DL 17 times this year, which is the most times they've used the DL since using it 21 times in 1997, when they were one of the worst teams in the Majors at 65-97.

The A's have used an MLB-high 45 players this year, and should Brown appear in a game, he would be the 46th. The Oakland record for most players used in a season is 49, set in 1997.