SARASOTA, Fla. -- When the offseason began, the Boston Red Sox made a priority of finding a reliever to pitch the eighth inning.
Now, as Opening Day beckons, the need has arisen all over again.
Already racing against the calendar to be ready for the start of the season, reliever Tyler Thornburg was scratched from a scheduled appearance here Monday against the Baltimore Orioles because of a spasm in his upper right trapezius. Considering Thornburg hasn't pitched in a major league spring training game since March 1 because of weakness in his right shoulder, he "most likely" will open the season on the disabled list, according to Red Sox president of baseball operations Dave Dombrowski.
Thornburg is expected to undergo testing, including a possible MRI exam, Tuesday. The Red Sox remain hopeful Thornburg won't miss significant time, so Dombrowski said he won't be active in trying to acquire another reliever.
"If it's what I anticipate, probably not," Dombrowski said. "But I can't rule anything out because I don't really know anything (other) than what we just found out, that he's got a trap that's tight. If it's a short-term situation, then I don't have a spot to offer somebody."
In Thornburg's absence, hard-throwing right-hander Joe Kelly is the first choice to serve as the setup man despite walking as many batters as he has struck out (seven) in eight innings this spring. Dombrowski mentioned righties Matt Barnes and Heath Hembree and lefty Robbie Ross Jr. as other candidates to handle the eighth inning.
The Red Sox acquired Thornburg in a Dec. 6 trade with the Milwaukee Brewers for infielder Travis Shaw and two minor leaguers, including touted infielder Mauricio Dubon. An apparent miscommunication over the Red Sox's shoulder conditioning program led to Thornburg taking longer than expected to build arm strength. He didn't pitch in games for nearly three weeks before finally throwing 20 pitches in a minor league game Friday.
Manager John Farrell said Thornburg's spasm "wasn't shoulder-related."
Thornburg was expected to pitch every other day this week, a schedule the Red Sox hoped would put him in line to begin the season on time. Even then, though, Farrell said Thornburg likely would be eased into the eighth-inning role for which he was acquired.
With Thornburg out, lefty Robby Scott could be in line to claim the final seat in the bullpen alongside Kelly, Barnes, Hembree, Ross, lefty Fernando Abad and closer Craig Kimbrel. Farrell also has been impressed with lefty Edgar Olmos and right-handers Jamie Callahan, Chandler Shepherd, Ben Taylor and Austin Maddox, although none of those pitchers is presently on the 40-man roster.
Earlier Monday, the Washington Nationals released 42-year-old reliever Joe Nathan, who indicated he has no plans to retire. Dombrowski signed Nathan before the 2014 season to be the Detroit Tigers' closer.
"I think we're fine," Dombrowski said, not referring specifically to Nathan. "Some guys have to step up is what it comes down to."