At that point, Boston manager Terry Francona emerged from the dugout along with assistant trainers Greg Barajas and Masai Takahashi. They met on the mound with Matsuzaka and the rest of the Red Sox infielders for several minutes before Francona elected to pull the right-hander from the game.
Matsuzaka left with a 4-2 lead, but he had walked four and given up three hits in throwing 82 pitches in four-plus innings. His performance Friday night was more characteristic of his time in Boston, with deep counts and a lack of command, unlike his previous two starts, when he had tossed 15 scoreless innings, giving up a total of only two hits in those outings.
Eventually, the Red Sox lost, 5-4.
Matsuzaka was replaced by Matt Albers.
Matsuzaka's next scheduled start would be Wednesday night against the Angels. Francona isn't ruling it out.
"I think we think he'll be OK for his next start," Francona said Friday after the game. "We'll check him out."
"I have an idea what's going on with my elbow right now so I'm not too worried about it," said Matsuzaka through a translator. "That kind of tightness happens sometimes. I don't really pay attention to it."
There was enough concern, however, to lift Matsuzaka from the game even though Dice-K said he thought he could have continued to pitch.
"We watched him between innings and it looked like he was stretching out his arm," said Francona. "We watched him out there. His velocity dropped significantly. We went out and he said it was stiff. He didn't put up a fight. We have to be cautious. It was hard to leave him in there."
Matsuzaka respectfully disagreed, but obediently left the mound.
"I could have continued to throw," said Matsuzaka. "I didn't feel I needed to come off the mound. I left the judgment to Tito. That was his decision to come off the mound. I understand Tito is always concerned about all his players. I feel sorry to make him concerned about my elbow."
Steven Krasner is a regular contributor to ESPNBoston.com.