Christian Vazquez (elbow) will receive a second opinion from Dr. James Andrews on Wednesday.
The Red Sox have named Clay Buchholz their Opening Day starter.
Red Sox manager John Farrell said that Koji Uehara is "not likely" to be ready for Opening Day after feeling more discomfort in his left hamstring during a bullpen session Saturday.
Ryan Zimmerman (shoulder) will take batting practice on Sunday.
Nationals manager Matt Williams admitted Sunday that Jayson Werth (shoulder) being ready for Opening Day would be "a stretch."