NEW YORK -- When Yankees starter Corey Kluber hit the injured list with a sub-scapular strain in his right shoulder, the expectation was that he would be shut down for four weeks before being allowed to pick up a baseball again.

But manager Aaron Boone said Thursday that there is hope for a more expedient return to throwing.

"I would say there's some optimism," Boone said. "He'll probably start a flat-ground program sometime in the next few days. But I'll probably have more when he gets here and we sit down and meet and start to map out a plan."

Despite the adjustment, Boone said the timeline for Kluber's return remains at two months.

The Yankees expect Kluber to fly back to New York on Thursday from Los Angeles, where he sought second and third opinions on the team's diagnosis. The team initially expected Kluber to be shut down for four weeks after he landed on the injured list May 27. In his last start, which was May 25, Kluber lasted just three innings, giving up a pair of runs.

Kluber signed a one-year, $11 million deal in the offseason after pitching just 36⅔ innings over the past two seasons due to injury issues.