The morning after CC Sabathia's knee started "barking," the left-hander has been placed on the 10-day IL.
A corresponding roster move was not announced.
Sabathia joins starting pitchers James Paxton and Luis Severino, who are also out with injuries.
Yankees manager Aaron Boone said after Wednesday night's game that Sabathia felt some discomfort in his knee. Boone described it as "barking a little bit," and noted a trip to the IL could be in the cards.
The issue is in Sabathia's right knee, which he has had issues with in the past. It has long been common for Sabathia to feel some pain in that arthritic right knee, which he had surgery on on Oct. 12. Sabathia has battled through it over the past few seasons, wearing a brace to help alleviate the pain.
This is the second IL stint this season for Sabathia, who got off to a slow start due to his offseason heart surgery. He underwent an angioplasty in December that required him to work slowly back to his normal self.
When he's pitched this season, Sabathia has been very consistent just as he was in 2018. He owned a 2.97 ERA through seven starts coming into Wednesday night's game. That changed for the worse after he allowed five runs (four earned) on six hits (two homers) over 5.0 innings. He struck out seven and walked two.