Forty-year-old Bartolo Colon will make his 394th career start on Sunday.
Twenty-four-year-old Brandon Workman will make his first.
Workman, Boston's second-round pick in the 2010 First-Year Player Draft, will face the A's in Sunday's affair in Oakland, the conclusion to the season's first half.
"We know he's going to throw strikes, that's the one thing he's proven over his Minor League career," Red Sox manager John Farrell said of Workman. "He's been a good strike thrower, and this is a team that forces you to throw strikes against them. We're looking forward to seeing him in the starter's role."
Workman, who is Boston's No. 13 prospect, made his Major League debut on Wednesday, when he tossed the final two innings of a blowout victory against the Mariners. The right-hander surrendered three runs on four hits in his first frame before bouncing back to spin a perfect second inning. He tallied four strikeouts and didn't walk a batter.
"Hopefully he takes the second of inning of work the other night in Seattle to the mound [Sunday]," Farrell said. "He's going to be back into his normal routine having started many games in his pro career. I'm sure there was a lot of adrenaline the other night coming in after the game was already underway. He was much more under control that second inning of work, particularly that balanced strike zone with all of his pitches."
The organization's Minor League Pitcher of the Year last year, Workman compiled an 8-2 record and 3.21 ERA in 17 outings (16 starts) split between Double-A Portland and Triple-A Pawtucket this season.
Colon, on the other hand, is slated to pitch in his 400th career Major League game. The right-hander, headed to his third All-Star Game this week, is 12-3 with a 2.69 ERA in 18 outings this season. It's his highest win total since he totaled 21 victories in 2005, when he merited the American League Cy Young Award with the Angels.
"I've never had a year like this," Colon said. "I believe this year is my best year. It was always in my thoughts, but I never imagined having the kind of numbers that I do right now before the All-Star break."
Red Sox: Thornton happy with his new club
• Matt Thornton was thrilled to join the AL East-leading Red Sox, who acquired him from the White Sox on Friday night. The southpaw went 0-3 with a 3.86 ERA in 40 appearances with Chicago.
"They're a first-place team," Thornton said. "It's all about winning in this game. That's why I prepare the way I do in the offseason, to win ballgames."
A's: Melvin undecided on post-break rotation
• Manager Bob Melvin has yet to set the order for his starting rotation following the All-Star break. Colon's availability for the Midsummer Classic will likely influence the arrangement.
Colon has not yet declared himself ineligible for Tuesday's exhibition. The A's play the Angels in Anaheim on Friday.
"Once we get through the break, then we'll map it out," Melvin said. "Part of it has to do with [Colon]."
• With a win Sunday, Boston would capture its 20th series victory of the season, which would match the club's total from the 2012 campaign.
• Red Sox reliever -- and former A's closer -- Andrew Bailey has tossed four scoreless outings in July after posting a 10.13 ERA in June.