Tanaka had the worst start of his MLB career Tuesday night, surrendering five runs and 10 hits in 6 1/3 innings against the Cleveland Indians.
An earlier report from the New York Post said Tanaka flew back to New York Wednesday to undergo an MRI on his right arm.
Tanaka was named to the American League All-Star team last week. He leads all major league pitchers with 12 wins, and his 2.51 ERA is second in the AL, trailing only Felix Hernandez of the Seattle Mariners. Tanaka's 9.39 strikeout rate is third among rookie starters.
The Yankees traded for Brandon McCarthy on Sunday to bolster their rotation, but McCarthy was supposed to take the spot of Vidal Nuno. Tanaka's injury leaves the Yankees with another hole in their rotation. Rookie Shane Greene started in place of Nuno on Monday, while McCarthy traveled to catch up with his new team. McCarthy makes his Yankee debut Wednesday.
The Yankees recalled outfielder Zoilo Almonte from Triple-A Scranton-Wilkes Barre to take Tanaka's spot on the roster. Almonte was in the Yankee lineup Wednesday in left field.
MORE MLB: Is Tanaka finally coming down to earth?
-Alex Hampl and Dan Gartland