"I felt some extra soreness there after the outing in Toronto [on Wednesday]," Tanaka said through an interpreter. "I thought that it would affect my performance if I were to pitch on Monday."
The current plan is for Tanaka to rest his arm for about five days before he resumes throwing again. Girardi also said Tanaka does not need any shots to bring down the swelling. The Yankees believe rest is the best remedy in this case.
"I don't think this will be too long," Girardi said. "He needs a break."
News of Tanaka's injury comes just a day after the Yankees placed veteran left-hander CC Sabathia on the 10-day DL with right knee inflammation, leaving two holes in the Yankees' rotation. Only a week ago, it looked as though the Yankees might have too much starting pitching after trading for Sonny Gray and Jaime Garcia, given the success rookie Jordan Montgomery has had this season.
Montgomery, who was in the rotation for much of the season, will start in Sabathia's place on Sunday night against the Red Sox. But the Yanks haven't named a starter for Monday's contest with the Mets, a game that Tanaka was scheduled to start.
Girardi said the leading candidates to start on Monday are right-handers Bryan Mitchell and Luis Cessa. The Yankees called up righty Giovanny Gallegos from Triple-A Scranton/Wilkes-Barre to serve as a long man in the bullpen and take Tanaka's place on the 25-man roster.
Another option to fill Tanaka's slot in the rotation could be right-hander Chance Adams, the Yankees' No. 3 prospect, according to MLB Pipeline. Adams is on a tear in Triple-A this season, posting a 9-3 record with a 2.31 ERA in 17 starts. However, there has been no word on whether the Yankees are considering calling him up.
Tanaka first mentioned the soreness to Girardi on Thursday, the day after his start against the Blue Jays. In that outing, he labored through four innings of three-run ball (two earned), throwing 88 pitches.
Toward the end of that start, Tanaka realized his arm didn't feel right. At that point, he said, it started to affect his performance -- as he struggled to put batters away and lost some of his command.
Matthew Martell is a reporter for MLB.com based in New York. This story was not subject to the approval of Major League Baseball or its clubs.