Masahiro Tanaka to play catch

— -- BOSTON -- Monday will be one of the most important days of the season for the New York Yankees playoff hopes, and not just because they're facing defending AL Cy Young Award winner Max Scherzer and the Detroit Tigers.

It's because earlier in the day, Masahiro Tanaka, their fallen ace, will test out his injured right elbow for the first time since he received a platelet-rich plasma injection on July 14 in the hope that he could avoid Tommy John surgery for a partially torn ulnar collateral ligament. According to a source in the Yankees clubhouse, it has already been decided that Tanaka will play catch on the field at Yankee Stadium.

"He'll definitely throw," the source said. "He's already told the doctors that he feels better."

Joe Girardi, as is his nature, refused to commit to a Tanaka throwing session by saying cryptically, "Catch or no catch. Those are the options."

But he did acknowledge Tanaka had seen the Yankee doctors on Friday and that, barring a setback Monday morning, was likely to pick up a baseball for the first time since July 8, when he was knocked out of a game for the first time in his brief but stellar big league career as he allowed five runs, including two home runs, in 6 2/3 innings against the Indians in Cleveland.

"We'll see tomorrow what everyone wants to do with him, but as we said, three weeks is the mark," Girardi said before Sunday night's game between the Yankees and the Boston Red Sox at Fenway Park. "[He told] his doctor he feels good, so we'll see what we do. We'll get home and talk and decide what we're going to do."

Even if Tanaka's game of catch goes well, Girardi said it was unlikely the Yankees would get him back before September, as previously noted by general manager Brian Cashman.  David Phelps, who started the Yankees' 8-7 Sunday night win over the Red Sox, left after just 2 innings due to right elbow inflammation. He will be evaluated further in New York this week.