MINNEAPOLIS -- Yankees right-hander Alfredo Aceves suffered a setback while tossing on Tuesday at the club's Spring Training complex in Tampa, Fla., and will be sent for further tests.
Yankees manager Joe Girardi said that Aceves completed about six or seven throws on flat ground before feeling discomfort in his lower back, cutting his session short.
Aceves has been on the 15-day disabled list since May 12 and also missed time during Spring Training with the lower back issue, which he believes to be a bulging disc problem.
"I thought there was improvement -- he was bouncing around better," Girardi said. "But he felt something. That's the thing about a back; you never know when it's going to act up. It's not what we wanted."
The Yankees have mixed and matched to cover for the absence of Aceves, who started the season as a long reliever and was 3-0 with a 3.00 ERA in 10 appearances before going on the shelf.
"There's no doubt we miss him," Girardi said. "He does fill a couple of different roles."