Song, who was placed on Double-A Portland's 60-day injured list Wednesday, is slated to undergo Tommy John surgery in the near future, Chris Hatfield of SoxProspects.com reports.

Song was returned to the Red Sox on Friday, Rob Bradford of WEEI.com reports.

The Phillies reinstated Song (back) from the 60-day injured list Saturday and designated him for assignment.

Song's (back) rehab is moving to Triple-A Lehigh Valley, where he will pitch Saturday, Matt Gelb of The Athletic reports.

Song (back) has been transferred to Double-A Reading to continue his rehab assignment.

Song (back) will begin a rehab assignment Wednesday with Single-A Clearwater.

Song (back) is on track to begin a rehab assignment next week, Todd Zolecki of MLB.com reports.

Song (back) threw a two-inning simulated game Tuesday, Alex Coffey of the Philadelphia Inquirer reports.

Song (back) will pitch in some simulated games next week, Alex Coffey of The Philadelphia Inquirer reports.

The Phillies transferred Song (back) to the 60-day injured list Friday.