Yarbrough is scheduled to work behind opener JT Chargois for Friday's game in Boston, Marc Topkin of the Tampa Bay Times reports.
Yarbrough will be making his 16th appearance of the season Friday and his seventh while coming out of the bullpen. He's turned in similar results as a reliever (4.38 ERA, .357 wOBA in 24.2 innings) compared to a traditional starter's role (4.46 ERA, .323 wOBA in 40.1 innings), but he claimed his lone win of the season while working as a primary pitcher Aug. 15 against the Yankees.