Tanaka was comfortable in two minor league rehab starts for Triple-A Scranton/Wilkes-Barre but will be under close watch, including a pitch count of about 80, Girardi said Thursday.
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Tanaka, 26, owns a 3.22 ERA, a 0.94 WHIP and a 24:7 strikeout-to-walk ratio in 22 1/3 innings this season. He was pitching through a partial tear in the ulnar collateral ligament in his elbow, an injury he suffered last season.