ARLINGTON -- There was no need for Robin Ventura to revisit a discouraging point he has made five or six times over the past few weeks prior to Thursday night's 3-1 victory over the Rangers.

But after starting pitcher Jake Peavy was scratched from the series finale against the Rangers with back spasms and replaced by Hector Santiago, the White Sox manager repeated those words now reverberating throughout the collective psyches of White Sox fans.

"It can always get worse," said Ventura, when asked by the media about the rash of injuries sweeping across his team.

Six White Sox players already reside on the disabled list, and while Peavy doesn't look to be joining them at this point, he won't be back on the mound until Saturday in Kansas City at the earliest. Peavy has never experienced back problems, but felt something in his back before Wednesday's game following a yoga stretch done by White Sox players during warmups.

Peavy received treatment all night and into Thursday to see if he could take his regular turn. When it was decided he couldn't, Santiago was moved up one day for his first scheduled 2013 start.

"I physically cannot pitch," said Peavy, who felt the pain and his back lock up when he went to pick up his glove after Wednesday's stretch. "I begged and begged to see if we could give it as much time as we can do, just for today. It wasn't going to happen. I hate doing this to the guys and hate not being able to go, but you got to do what's best for the team, and it's me not going out there tonight."

"You are just kind of waiting to see how he was today, but the way things are going for us right now, it's not time to start chancing it," Ventura said. "Late in the year you can probably do that. The way he's feeling today, there's no reason to send him out there and cross your fingers he doesn't get hurt."

Dylan Axelrod will pitch on regular rest Friday night in Kansas City, weather permitting, but the White Sox still need a starter Saturday. Santiago threw 86 pitches in relief of Gavin Floyd last Saturday night at home against the Rays, so he worked Thursday on regular rest.

Over five starts this season, Peavy has a 3-1 record with a 3.38 ERA. He has fanned 39 and walked six in 32 innings.

He clearly didn't see this injury coming, and the White Sox can't afford to lose their pitching leader. As Ventura understands, it can always get worse.

"To walk and pick up your glove and something grab you and make you fall to your knees is out of the blue and unexpected," said Peavy, who appeared to be moving slightly better after Thursday's win. "Like we said all along and watch guys make progress in the training room, we have a great team and medical staff that hopefully will get myself and the other guys on the field as soon as possible.

"I've never had anything like this happen. Maybe a muscle relaxer and some treatment I was hoping would do the trick last night and be able to go today. It wasn't the case. I'm sure we'll sit down with the staff and try to come up with a game plan and see what the doctors and trainers think is the best case scenario."