Ellsbury hasn't played since March 14. He was scratched from Sunday's game against Atlanta because of right calf tightness.
''I'm sure he'll take BP tomorrow,'' Yankees manager Joe Girardi said before Thursday night's game against Boston. ''We just wanted to make sure he was OK. They decided to do a precautionary. I don't determine if a guy gets a test. That's our guys on the medical side. ''Our people just decided let's be cautious and make sure. We got good news.''
Girardi said he did not have a specific number of days planned for Ellsbury to rest.
''We want to get him out there and get ready for the season,'' Girardi said. ''As soon as we can get him out there, we'll get him out there.''
Girardi said he hoped Ellsbury would play this weekend or by Tuesday.
''We can accelerate with games in the minors,'' he said.
Ellsbury agreed to a $153 million, seven-year contract in December after helping the Red Sox win a pair of World Series titles during seven seasons in Boston.
Yankees shortstop Brendan Ryan was scratched from the starting lineup Thursday because of upper back spasms.
Ryan had been limited to nine plate appearances because of a lower back issue. The Yankees said the spasms are unrelated to the earlier problem.