"My strength is the same," said Severino, who suffered a shoulder injury minutes before a scheduled start against the Atlanta Braves on Tuesday. "I feel like something pulled."
An MRI late Tuesday afternoon revealed that Severino had right shoulder inflammation. It apparently set in after Severino threw a slider while throwing warm-up pitches at George M. Steinbrenner Field.
Severino said he didn't throw another pitch after he felt the twinge.
This was the first time Severino has experienced pain after throwing a slider. He went through a simulation game on a back field last Thursday and made it through with no issues, he said.
Because of the injury, manager Aaron Boone said Severino would be shut down for the next two weeks. Severino will take a cycle of anti-inflammatory medication as he rests his shoulder.
"Hopefully it's as short as necessary, but we need to make sure we give it the time also that's necessary," general manager Brian Cashman said Wednesday. "He's an important piece and we're not going to have him for a period of time.
"We'll adjust. That's what everybody has to do. But it's obviously a very concerning situation until he's on the mound for a consistent amount of time to the point that you forget it ever happened."
Cashman said Severino was due to receive a cortisone shot at some point Wednesday.
The Yankees hope Severino will be able to resume a throwing program after his two-week break. Boone said it was "highly unlikely" that Severino would start Opening Day as had been planned.
"It's frustrating, because the bad thing about baseball is you don't [always] get to play baseball," Severino said. "This is the game that I love, and I want to be there for the team. It's going to be tough for a little bit, but after that, like I said, it's better it happened now than in midseason or at the end of the season.
"God has a plan for everybody, so it's better now than later."
Although free-agent left-handed starter Dallas Keuchel remains unsigned, Cashman gave little indication that he would go after him or any other pitchers from outside the organization. He isn't completely ruling it out, but he seems lukewarm to the idea at the moment.
"What I've got is what I've got," Cashman said, "and we're comfortable with that. Can't rule anything out, but I'd say the main focus is what we have."
Cashman also said outfielder Jacoby Ellsbury, who has spent the start of spring training rehabbing at home in Arizona from a plantar fascia issue, is expected to rejoin the team in approximately 10 days.