MILWAUKEE – Though a statement issued by the team referred only to infielder-outfielder Mark DeRosa’s left wrist strain as reason for him landing on the disabled list, the Cardinals’ June 27 trade acquisition is apparently suffering from a torn tendon sheath that casts doubt on his return immediately following the All-Star break.

DeRosa confirmed the diagnosis Tuesday afternoon and refrained from offering a timetable for his return. This much is clear: DeRosa will refrain from all hitting for the near future. He admits that last week’s optimism was based more on hope than fact, and that Monday’s finding confirmed what he had suspected all along.

“I knew it when I did it,” DeRosa said. ”I tried to play the brave face. I know my body pretty well. I’ve had my share of surgeries and aches and pains. You know the difference between tweaking something that is manageable and something feeling wrong.”

A magnetic resonance imaging found the problem Monday. An exam last Wednesday proved inconclusive due to inflammation and swelling of the wrist, which De Rosa said “popped” during a June 30 at-bat against San Francisco Giants lefthander Randy Johnson. Team medical supervisor Dr. George Paletta examined DeRosa for the first time on Monday.

The diagnosis lands a body blow to the optimism caused by the trade that brought DeRosa to St. Louis as a long-sought answer at third base. DeRosa made three starts and took only nine at-bats before going down. Manager Tony La Russa started Joe Thurston at the position tonight.

“I don’t know all the jargon. But there is definitely something wrong with it,” DeRosa said. “There is definitely a partial tear of the sheath. It’s one of those things where you hope time allows it to heal itself.”

DeRosa took swings off a tee in Cincinnati last weekend. Initially portrayed as a positive sign, the workouts actually exposed lingering discomfort.

“It didn’t feel good but it didn’t feel excruciating,” he said. “I could have tried [to play] but I don’t know what the outcome would have been.”

The club has not offered a timetable for DeRosa’s return, though general manager John Mozeliak said earlier Tuesday that he remained “very optimistic” DeRosa would become available shortly, if not immediately, after the July 13-16 break.