Martinez, who is sitting for a third straight day Wednesday, is dealing with a sore back in addition to the illness that bothered him early in the week, Pete Abraham of The Boston Globe reports.
The back injury takes precedent over the illness, which he is probably over at this point. Abraham notes that Martinez may not play Thursday, in which case his availability for this weekend's series against the Astros could come into question. Christian Vazquez starts at DH on Wednesday.