Mookie Betts was a late scratch from Sunday's game because of tightness in his left side, the team announced.
Betts had been scheduled to bat leadoff as the Red Sox look to take their third straight from the Braves and improve on baseball's best record of 36-16.
Betts is in the midst of a monster season. His 17 homers lead the majors, and he's first in the American League in average (.359), OPS (1.187), doubles (19), and runs (52).
With Betts sidelined, Blake Swihart will make his first appearance in the outfield since suffering a serious ankle injury there in 2016 and bat seventh.
Here's the new lineup in support of left-hander Chris Sale:
Andrew Benintendi CFXander Bogaerts SSMitch Moreland 1BDustin Pedroia 2BRafael Devers DHEduardo Nunez 3BBlake Swihart LFSandy Leon CJackie Bradley Jr. RF