Girardi said Tanaka might need just one more outing, either a simulated game or at the Yankees' minor league facility in Tampa, before he returns to the rotation.
After pitching a simulated game in Detroit on Aug. 29, Tanaka reported "general soreness" in his arm.
Tanaka threw another simulated game on Tuesday and said he thought he was "throwing stronger, harder" than in his last simulated game, according to ESPN.com.
The Yankees want to see Tanaka face major league hitters this season in order to determine whether or not he should undergo surgery in the offseason, ESPN.com reports.
Tanaka is 12-4 with a 2.51 ERA this season. He was leading the American League in wins when he got injured.
- Dan Gartland