BOSTON -- Red Sox left-hander Matt Thornton left his relief appearance in the eighth inning of the Red Sox's 4-0 win Sunday vs. the D-backs with what he described as a right oblique injury.
After giving up a leadoff single, Thornton felt a cramping sensation while facing D-backs shortstop Didi Gregorius.
"After that, it started getting worse and worse," Thornton said. "It got more painful instead of a cramp."
Manager John Farrell and a trainer came to the mound and decided to take him out of the game.
"We'll check him tomorrow to see the severity of it," said Farrell, "but he felt it in the second pitch of that final at-bat and then a couple of pitches after that. You could see from the dugout he was starting to get a little bit more upright and protected. We clearly had to get him out of there."
Thornton, who has appeared in 10 games and has 2.16 ERA since joining the Red Sox in early July, said he felt good after the game. He met with team doctors and was told that how he feels Monday will be a determining factor on if he'll need to miss any time.
"They said that tomorrow is the today we have to worry about," he said. "We'll see how it feels tomorrow and figure it out."
Buchholz enthused by progress with pitching program
BOSTON -- In a sign that Clay Buchholz is again making progress in his prolonged comeback from a bursa sac strain in his right shoulder, manager John Farrell used the word "mound" to describe what could soon be on the right-hander's rehab agenda.
Since the All-Star break, Buchholz has been limited to flat-ground work.
"Continues to gain strength," said Farrell. "He feels more stability in each throwing session that he goes through. Today is planned to be another aggressive one for him. We would hope that after today, and tomorrow being a little bit of a normal recovery day for him, that we're getting closer to the mound and hopefully we'd be able to incorporate some work, whether that's continued crow hop off the mound or actually getting on it. I think the mound is definitely getting closer here."
A telltale sign for Buchholz will be when he can crow hop and throw the ball with 100 percent intensity.
Buchholz said that Sunday was his best day in that regard, as he estimated he threw at about 80 percent intensity.
"The highest intensity I've thrown was today," Buchholz said. "It was to the point where I'm not hoping or thinking something's going to happen or I'm going to feel something when I throw. I'm able to let loose a little bit more right now, and even if it's only four throws that are at a higher intensity than the day before that's encouraging for me, for the next time I go out and throw, to go out and play long toss. To get into it a little bit more."
Buchholz will sit down with Farrell and the training staff on Monday to determine the next step.
"It felt good [Sunday]," said Buchholz. "I played pretty extensive long toss. It was good. The last two days have been really good for me. Moving forward, we're trying to map out what I can start doing. I'm sure we'll talk about it tomorrow, because it's an off-day for me."
Buchholz said that this is the best he's felt since before the All-Star break, when he pushed a little too hard and had a setback during a throwing session in Oakland.
"I haven't felt this good throwing since there was a day in Seattle I played catch and didn't feel anything," Buchholz said. "That's sort of where we're at now. That's why I don't want to do too much at one time just to let everything figure itself out. Let the muscles start working together again. Yeah, obviously the next step is to get off the mound a little bit for a touch and feel type thing just to get back on the rubber."
Once he is able to throw off the mound two to three times without restrictions, the Red Sox could send him out on a Minor League rehab assignment.
Buchholz, who last pitched for the Red Sox on June 8, is 9-0 with a 1.72 ERA in 12 starts.
Nava out for Houston; Workman on way back?
BOSTON -- With Daniel Nava's wife scheduled to deliver the couple's first child in the next couple of days, the outfielder won't travel with the Red Sox for their upcoming three-game series in Houston and will be placed on the paternity leave list.
Nava will rejoin the Sox on Thursday for the start of a four-game series in Kansas City.
The Red Sox are allowed to fill that roster spot, and manager John Farrell said the team will likely use it for a pitcher.
This could allow right-hander Brandon Workman, who is transitioning to the bullpen and ranked the club's No. 11 prospect, to be called back up.
Workman, who was solid in his first three Major League starts for the Red Sox, was optioned to Triple-A Pawtucket on Thursday, mainly because Boston's bullpen was spent from a 15-inning game the night before.
Under normal circumstances, Workman would have to stay in the Minors for 10 days. However, he is eligible to replace a player who is placed on the disabled list, or, as in Nava's case, the paternity leave list.
Workman was scheduled to make his first relief appearance for Pawtucket on Sunday.
"It's not a scripted outing of, 'OK, it's two innings today.' We're going to kind of let this now work out of the bullpen with what the game might dictate," said manager John Farrell. "Hopefully it's a clean inning he comes in to start with. If not, we're not going to hold him to that, or hold the staff to that."
• Farrell celebrated his 51st birthday in the dugout, as the Red Sox hosted the D-backs on Sunday afternoon. Farrell shares the same birthday (including the year) as Roger Clemens. President Barack Obama was also born on Aug. 4, one year earlier than Farrell.
• Left-hander Franklin Morales (left pectoral strain) made a big step toward returning to the Red Sox by throwing 2 1/3 shutout innings for Triple-A Pawtucket on Saturday.
"The fact we're able to get him up multiple times now, 2 1/3 efficient innings, he'll have two days down and go two innings again. But the overall strike throwing, his comments coming out of it, how well he feels physically is encouraging," said Farrell. "Now that he's got the three outings under his belt, one being multiple innings, hopefully we're getting out of the woods, so to speak, with what he's been dealing with."
• With the Red Sox playing their next round of Interleague games in National League cities later this month (Aug. 19-25 at San Francisco and Los Angeles), the starting pitchers all took batting practice before Sunday's game.
Ian Browne is a reporter for MLB.com. Read his blog, Brownie Points, and follow him on Twitter @IanMBrowne. Michael Periatt is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.