The Rays' catcher already missed 43 games with a left knee sprain before this latest setback.
Lobaton caught a bullpen session Friday and said if he feels fine in the morning, he will likely catch Saturday against the Red Sox.
"Right now, it's tough," Lobaton said. "[I've] got a lot on my mind. I want to play at 100 percent, not 90 percent. ... If they say I can play, I can play."
Manager Joe Maddon said Monday that Lobaton and John Jaso would get the bulk of the catching duties for the remainder of the season, leaving Kelly Shoppach as the odd man out because the Rays want to get a good look at Lobaton.
Lobaton hit .293 with eight home runs and 31 RBIs at Triple-A Durham and he threw out 12 of 39 attempted basestealers. Lobaton is just 1-for-14 for the Rays, but he has played in just six games due to the injuries.