SARASOTA, Fla. -- Andy Phillips, who arrived at Spring Training with the goal of earning one of the final two bench spots the team had available, likely won't be able to return to action as soon as initially anticipated.

Phillips has been held out of action since March 7 after notifying the Pirates of stiffness in his lower back. He reported feeling better earlier this week, but had another setback on Thursday and has since had to postpone his return to the field indefinitely.

Phillips underwent a magnetic resonance imaging test, which revealed a couple of bulging discs in his back. That's not unusual for this sort of injury, but it is something that the Pirates are going to have let take care of itself before Phillips can work his way back to the field.

"It just doesn't feel right," manager John Russell said. "We're just really going to try and quiet [it] down before we get him back."

Russell said that Phillips is still able to do some exercises, but baseball activity has been halted. Russell also shied away from making any sort of prediction on how long it might take to get Phillips back.

"It's got to get better relatively soon," Russell said. "There's not much you can do about it. Anybody who has ever had lower back problems knows it's not fun. We'll just have to see how he continues to progress."

With only two weeks left in Spring Training, Phillips could very well be running out of time in his bid for a spot on the Opening Day roster. Before the injury, the 32-year-old utility player was seen as a frontrunner for a spot as an infield/outfield backup.

However, with no return date in sight for Phillips, that bench spot appears more likely to go to either Luis Cruz or Brian Bixler, since the Pirates would like an additional infield option.

Cruz's ability to play every infield position and as an outfielder might make him the more intriguing option of the two. However, Bixler has put together a strong spring showing and has made significant strides both defensively and offensively. Furthermore, infield instructor Perry Hill said he plans to work with Bixler at first base in order to increase his versatility.