BOSTON -- Red Sox outfielder Jacoby Ellsbury said he still felt sharp pain in his left chest area while taking batting practice Tuesday, leading the club to place him on the 15-day disabled list.
Darnell McDonald, who was on standby somewhere in the vicinity ("a secret spot,'' McDonald joked), was in the clubhouse before the game and was immediately activated. McDonald became the second outfielder from Triple-A Pawtucket within hours to join the Red Sox, Josh Reddick having already been summoned to replace Mike Cameron.
Cameron was diagnosed with an abdominal tear and placed on the 15-day disabled list on Monday. The outfielder was hopeful that the injury will heal with rest, calling surgery a "worst-case scenario.''
"My stubbornness sometimes gets in the way,'' said Cameron, who played Sunday despite being in considerable pain and going to the hospital after the game, the original suspicion that he had another kidney stone like the one he passed Friday.
Instead, tests showed a tear of the abdomen.
"I went as long as I could as hard as I could,'' Cameron said. "The stone was probably a mask for me that allowed me to play. If it was anything else, shoulder, groin, I'd probably still try to play. But where this is located, there's nothing else you can do.
"I was in pain, as painful as it gets,'' he said.
Sox general manager Theo Epstein said he believes Cameron's condition contributed to him dropping a liner in the first inning against the Rays on Saturday that led to four unearned runs.
"I didn't have a choice,'' Cameron said of playing Saturday. "I had to try. I'm not going to make excuses. I've never been one who believes in that.''
Cameron's agent, Mike Nicotera, said doctors were amazed that Cameron played the next day as well.
"The doctors who examined Mike believe that the reason Mike was actually able to play the last few days with this injury was a result of the few days' rest he got while dealing with the kidney stone,'' Nicotera said. "Although both conditions affected his lower abdomen, they were not at all related. Just an unfortunate coincidence.
"Mike has always been a quick healer and he is optimistic that rest during his DL stint will be sufficient to get this resolved.''
Cameron said that doctors did not give him anti-inflammatories because they feared he would feel so much better he'd be angling to play before he was ready.
''I was disappointed because I know what we're going through as a team," Cameron said. "The last thing you want is not being on the field. But sometimes things happen where it's better to step back now and be available the rest of the year.''
Cameron said he could not pinpoint a single cause of the injury. "Just the constant grinding,'' he said. "They talked about the different things your body goes through.
"I certainly hope to avoid surgery.''
With Ellsbury, the Red Sox had pointed to Tuesday's batting practice as the final determinant of whether he would be activated. He said he took the first round rather gingerly, did some easy running around the bases, then stepped in for a second round, when it became evident that he has not improved enough to return to the field.
Ellsbury said he talked briefly with Rangers outfielder Josh Hamilton, who went on the DL and missed 13 games last spring after straining a left rib muscle.
"It's just one of those things that takes time,'' said Ellsbury, who said he continues to have trouble drawing a deep breath and also experiences sharp pains.
Ellsbury's disablement was retroactive to April 12. He is eligible to come off the DL next Tuesday in Toronto.
Reddick, 23, was batting .179 (7-for-39) with one homer and six RBIs in nine games for Pawtucket this season, but had a double, triple and home run with four RBIs and four runs scored in his last two games.
McDonald, 31, was hitting .341 (14-for-41) with six doubles, a triple, and two home runs, eight RBI, six runs and one stolen base in 10 games with Pawtucket in 2010. Signed by the Red Sox as a minor league free agent on Nov. 24, 2009, McDonald has appeared in 68 major league games over parts of three seasons with the Orioles (2004), Twins (2007) and Reds (2009). He has hit .231 (34-for-147) with seven doubles, one triple, two home runs, and 11 RBIs.
Gordon Edes covers the Red Sox for ESPNBoston.com. Follow him on Twitter.