"I threw harder this time," said Kuo. "It feels all right, normal, not too bad. It's getting better."
Manager Joe Torre said that Kuo is close to beginning a Minor League rehab assignment but might need to throw to live hitters first.
Kuo's absence has been compounded by the continued problems of the only other lefty in the bullpen, George Sherrill, who let Saturday night's lead get away.
"I talked to Sherrill today," said Torre. "He had good stuff in the bullpen. He's worked so much on his mechanics, I told him to go out and just compete. Sometimes you think about too many things and don't just go out trusting. I said to forget about the other stuff."