The suit, in State Supreme Court in Manhattan, came just days after Rodriguez’s lawyers began appealing the 211-game ban issued by baseball. The appeal is being conducted through a closed arbitration hearing at baseball’s headquarters on Park Avenue in Manhattan, and it is unclear if the suit will affect those proceedings, which ran all this week and will resume in mid-October.

The suit, which seeks unspecified damages, does not address whether Rodriguez used banned substances.

Nor was it the only suit that Rodriguez and his lawyers filed. On Friday evening, Rodriguez lodged a second lawsuit, in State Supreme Court in the Bronx, charging that the Yankees’ team physician, Dr. Chris Ahmad, and NewYork-Presbyterian Hospital had been careless and negligent in the manner in which they treated him for a hip ailment last October.

At the heart of the suit is the contention that a magnetic resonance imaging test that Rodriguez underwent at the hospital revealed a small tear in his left hip, but that neither the Yankees nor Ahmad immediately informed Rodriguez about the finding and that he continued to participate, injured, in the American League playoffs.

However, it is not clear if either Ahmad or the Yankees were initially aware that the M.R.I. showed a tear in the left hip, since Rodriguez, when he went to the hospital, was complaining of pain in his surgically repaired right hip. The M.R.I. did not show a new tear in that hip.