Ellsbury ran the bases and hit on the field at Minute Maid Park on Saturday afternoon. He will do so again on Sunday, and if all goes well, manager Joe Girardi said that Ellsbury could be sent to the team's complex in Tampa, Fla.
"The next two days are kind of important," Girardi said. "If we can get through these couple of days where he does well, we could really start to talk about a rehab assignment. Then you're talking about him getting pretty close. The next two days are important, the running and being able to go 100 percent."
Ellsbury has not played in a game since May 19, when he sustained a strain of his right lateral collateral ligament while batting against the Nationals in Washington, D.C. He was hitting .324 (48-for-148) with one homer, six RBIs and 14 stolen bases in 37 games.
Girardi said he doesn't believe that Ellsbury will need many at-bats in Minor League games to be ready.
"We'll evaluate that. It's really hard to tell," Girardi said. "You've got to really know how a guy is feeling. If he feels good at the plate, sometimes they don't need many. If they don't feel good they may need a few more. I don't ever put a number on it. I think the important thing is, once he plays, how does he feel the next day? That's the important thing for me."
In Ellsbury's absence, the Yankees are using Brett Gardner and Chris Young in center field. They have also given opportunities to rookies Slade Heathcott and Mason Williams, both of whom have since joined Ellsbury on the disabled list.
"We've done OK. We've definitely missed him," Girardi said. "We've had a number of people that we've tried to use in his absence. He's not a guy that you can really replace. I give our guys a lot of credit. They've played pretty well, whether it was Slade or Mason or Chris Young, who's done a really good job. You can't replace him, you just hope you can put someone in there who can do the job and they've been doing it."
• Yankees closer Andrew Miller (left forearm flexor muscle strain) made 45 tosses at approximately 100 feet on Saturday afternoon. The Yankees will evaluate Miller on Sunday to see how he bounces back from that session.
Bryan Hoch is a reporter for MLB.com. Follow him on Twitter @bryanhoch, on Facebook and read his MLBlog, Bombers Beat. This story was not subject to the approval of Major League Baseball or its clubs.