"It sort of happened at the right time for them, but the worst time for me," said Buchholz, whose scheduled Sunday start at Fenway Park against Milwaukee will now be taken by right-hander Josh Beckett.
With a scheduled off-day Thursday, the Red Sox figure they can keep the rest of the starting rotation on turn. But it will take longer for Buchholz's fingernail to heal, and Boston needed the roster spot to accommodate the recall of outfielder Jonathan Van Every from Triple-A Pawtucket.
"I've had a fingernail bend, but never one that just came off," said Bucholz, who is 2-3 with a 5.53 ERA in eight starts. "It went all the way off and I just had to end up tearing it off. It was really tender toward the end of the outing. [Tuesday] and today, it feels fine. I feel like I could throw."
The issue cropped up when Buchholz was warming up before the second inning of Monday's start at Minnesota. A two-seam fastball was the culprit, and Buchholz resisted the temptation to beg out of the game before departing after 4 1/3 innings after allowing seven runs on eight hits and five walks.
"I knew something had happened when I threw it, so I didn't even look at it," he said. "I just kept throwing and when I went in the dugout, it was bleeding a bit and I didn't tell anybody. It's my own fault, I guess."
The pain from the exposed nail bed caused Buchholz difficulty in gripping his fastball.
"I could only feel it when I threw fastballs, so that's why we strayed away from throwing fastballs and went to a lot of changeups and curveballs, because I couldn't feel it," Buchholz said. "Whenever they did call a fastball, I tried to throw it as hard as I could because regardless of how much pressure I put on it, I could feel the pain. I just tried to let it go and most of the time, the pitch wasn't where I intended to throw it."
After being examined, Buchholz was told the Red Sox were going to take a cautious approach. As recently as Tuesday night, he was still scheduled to start Sunday.
Bench coach Brad Mills, who is managing the Red Sox while Terry Francona attends the funeral of his mother-in-law in Arizona, said Buchholz was being shelved so that he didn't cause further injury by trying to compensate for the fingernail problem.
"The thing that we were concerned about there is that it was going to alter how he threw," Mills said. "He's going to need some time anyway to have that fingernail heal, so if he was going to alter [his delivery], that might go into his elbow or his shoulder."
So Buchholz will get an unplanned break.
"I've got to do what they tell me to do," Buchholz said. "I don't like not being able to pitch for a couple of weeks, but it is what it is. We've got a couple of people who have gone down with injuries, so I've got to bide my time."
Pete Kerzel is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.