Boston Red Sox relief pitcher Chris Carpenter, the main compensation sent east in the unusual offseason trade, will undergo surgery on his right (throwing) elbow to remove a bone spur, according to a pair of messages Tweeted from his personal account on the social media website Wednesday afternoon.

In the message, Boston's No. 8 prospect wrote that Dr. James Andrews, who is based in Birmingham, Ala., would perform the surgery.

Carpenter, who last pitched March 19, was battling for a spot in Boston's seven-man bullpen. He went 0-1 in two Spring Training appearances, allowing four runs on two hits and five walks over 1 2/3 innings. He was likely ticketed for Triple-A Pawtucket.

"Like every year, I came into Spring Training wanting to pound the zone, to show I can throw strikes with all my pitches," the 26-year-old right-hander told MiLB.com earlier this month. "Commanding my fastball is something I have been working on, and hopefully it keeps improving."

Epstein, the Cubs' new baseball operations czar, announced Feb. 21 he was shipping Carpenter from Chicago. (The exec also sent Minor League pitcher Aaron Kurcz to fulfill its end of the two-way, player-to-be-named-later swap.) Carpenter compiled a 2.79 ERA in his first 10 Major League relief appearances last season.

The timetable for his return to the mound was unclear. Baltimore Orioles right-hander Jake Arrieta reportedly underwent surgery to remove a bone spur from the joint on his pitching elbow last August and has pitched in three Spring Training games this month. Arrieta is on track to pitch Opening Day.

At 4:01 p.m. ET on Wednesday, Carpenter followed up his first Tweet by writing on his Apple iPhone: "Stayin [sic] positive and prepared to work harder than ever to come back as soon as I can this season! #dedication #onamission #redsoxnation".