"I'm good. It's gotten better every day," said Hafner, who signed a one-year contract with the Yankees in February. "Basically, we'll just continue to rehab until it's strong enough."
Without Hafner, the Yankees have rotated players at DH, including Vernon Wells, Alfonso Soriano and Alex Rodriguez.
Before going on the DL, Hafner was hitting .205 with 12 home runs and 37 RBIs, and had a .300 on-base percentage in 81 games. Hafner hit .318 with six home runs through the first month of the season, but fell into a slump that lasted until he was placed on the disabled list.
Through May, June and July, Hafner hit .167 in 59 games. His last home run came on June 25. Hafner experienced a sore shoulder in mid-May, but received a cortisone shot to relieve the pain at that time.
Hafner, 36, said he wasn't sure if the shoulder pain that cropped back up contributed to his lack of production at the plate. But he said the pain was at its worse in his last game on July 26.
"It was just a little sore at the start of that last game, and by the end of that game, it had gotten pretty bad," Hafner said. "Within a matter of a couple of hours, it just lost all strength. I don't know."
There's a chance Hafner could return to the team this season, though he said he'll have to go through a hitting program and will then probably play in some rehab games. He said he's going to be checked again once the Yankees return from their upcoming weekend series in Boston.
Right now, Hafner is completing only shoulder exercises. He said it'll at least be September by the time he returns, but is optimistic he'll be back on the field before the season is over.
"I don't have a very good feel," Hafner said, "but it's improving every day, so that's encouraging."
Chris Iseman and Josh Vitale are associate reporters for MLB.com.