PORT CHARLOTTE, Fla. -- For 11 days since his scary outfield collision with Rays teammate Desmond Jennings, B.J. Upton hasn't been able to get back on the field.

The real question is how many of the next 11 days he'll be able to play, and whether it will be enough to allow him to play on opening day against the Yankees.

"It's pretty close to the point where he may not be able to get ready," manager Joe Maddon said Sunday, as Upton went through another day where he was too sore to play.

Upton has had only 17 at-bats this spring. Maddon prefers that his regulars get anywhere from 50-60 at-bats. While Upton won't get anywhere near that, there's still hope that he could get enough -- if his sore back heals soon.

"When I'm ready, I'm ready," Upton said. "If you're asking about opening day, I should be ready for it. It is getting better. . . . Opening day's closing in, but if I can get the last full week in, I should be fine."

Starting with Monday, the Rays have 10 spring training games remaining.

Jennings has healed faster than Upton, and with Sam Fuld also hurting, there's a chance that Jennings could be shifted to center field for opening day if Upton can't make it.

The Rays are also watching the health of shortstop Reid Brignac, who played in a minor-league game Sunday.

Also, the Rays still need to set the final two spots in their starting rotation. Matt Moore is expected to take one of them, and the guess has been that they'll eventually keep Jeff Niemann in the rotation and send Wade Davis to the bullpen.

Davis was set to start Sunday against the Marlins, and Niemann starts Monday against the Twins. A decision should come soon after that.

"Whoever's going to go to the bullpen is going to be upset," Maddon said. "You'd like to give them a few days to be upset before the season starts."