"[Phelps] has now a different little strain [in his forearm]," Girardi said. "It's different from the last one. The last one healed, so he has a little one. It's in a different spot, so he'll be off for a couple of weeks. … I think they said they'd shut him down two weeks."
"It's very small -- this is a minor strain," Yankees general manager Brian Cashman said. "It would be less than Grade 1, but it's still a strain nonetheless. … It's minor, but it's something you've got to be careful of, so you back off."
Pineda, who has been recovering from right shoulder surgery, felt stiffness in the shoulder during a start for Triple-A Scranton/Wilkes-Barre on Friday. He went to New York to undergo tests.
The 24-year-old Pineda hasn't pitched a Major League game for the Yankees since they acquired him in a trade with the Mariners in January 2012. Between Class A Advanced Tampa, Double-A and Triple-A this season, Pineda has gone 2-1 with a 3.32 ERA in 10 starts.
"Pineda just had some tightness," Girardi said. "The tests came back good; the strength was good. He'll be shut down -- my guess is seven to 10 days."
Cashman said that the most important thing for Pineda is to finish the season without any more injury issues.
"The testing today … appears to have gone as well as can be expected," Cashman said. "That doesn't mean anybody's out of the woods. He'll be shut down for seven to 10 days, then get his throwing program back. What's best for him right now and best for us is just to finish this year healthy ... so we can have him in our mind next year as a player we can count on."
Cashman added that he doesn't know whether Pineda will pitch in a big league game before the end of this season.
"I don't know if you'll see him or not this year," Cashman said. "The doctors told me, 'Yes, you can see him this year.' Will we see him? I don't know. And is that what's best? I don't know."
Manny Randhawa is an associate reporter for MLB.com. Follow him on Twitter at @MannyBal9. This story was not subject to the approval of Major League Baseball or its clubs.