Matsuzaka had been experiencing previous issues in his trapezius area and recieved an injection to the muscle this weekend.
"The same area flared up a little maybe three weeks ago. It was the same symptoms," said Matsuzaka, through a translator. "It seemed to have cleared up, but it came up again. It restricts my movement when I throw. At this point, that's why I got the shot. Hopefully it gets better from here. My rehab so far had been going really well, so it is a setback and it is a little disappointing."
"We expect that this issue will resolve, because he's had it in the past and it's resolved," said Sox general manager Ben Cherington. "So we expect it will resolve and when that happens we'll get him ramped back up and out pitching."
The righty is the latest in a long string of injured Sox starters. Outfielder Cody Ross recently suffered a fracture in his left foot after fouling a ball off himself. The injury will not require surgery, but Ross will be sidelined for 6-8 weeks. Third baseman Kevin Youkilis is also currently nursing back issues in the minors and will remain on the Pawtucket Red Sox roster until Tuesday at the earliest.
Despite the slew of abscences in the Sox lineup, Daiskue is in no hurry to rush his recovery. He will restart his 30-day rehab cycle after taking a week off and hopefully, he has better luck this time.
"I've said this before, but I don't want — and I don't think I can — pitch until I'm 100 percent physically and mentally," Matsuzaka said. "I haven't felt 100 percent yet but I have felt like I'm approaching 100 percent."
Matsuzaka could return to the mound as soon as Saturday, but at this point, the emphasis will be on making sure he's fully healthy before it gets to that.
