"It all depends," La Russa said. "We are trying to protect our bullpen over the weekend. [On Friday], we got eight innings. We will see what happens today, and then we will see what happens tomorrow. It's one day down, and two more to go."
La Russa said Ponson could possibly throw in relief on Saturday.
"I don't know," the manager said. "If he threw today, it would just be three outs. If he has another day off, then he can go more than that."
Ponson hasn't worked past seven innings in any of 10 starts this season, but that wasn't a factor in the move.
"It's not one of the things that our staff has been featuring this year," La Russa said. "It's not something to single him out for."
Spiezio starts: For just the second time since May 26, Scott Spiezio saw his name on the lineup card for Saturday's contest against the Rockies.
Over the last few weeks, Spiezio had missed multiple games and was limited to pinch-hit duties in several others because of an upper respiratory infection.
Saturday, though, he came to the ballpark feeling better. Playing first and batting fifth, he hoped to play the full game.
"I am not where I should be, but I am still better than I was," Spiezio said. "I don't think there will be any problem. I just want to play the first nine at first base before moving on."
Cardinals manager Tony La Russa said the start was a few days in the making.
"I told him in Pittsburgh that I would like to start him in the game on Saturday," La Russa said. "If he wasn't ready, then we would go to Plan B."
Spiezio, hitting .293 in 99 at-bats this season, said he didn't feel any problems after taking a pinch-hit walk and running the bases in the eighth inning of Friday night's game. In previous pinch-hit appearances, Spiezio seemed tired and even light-headed after running.
Eckstein sits: David Eckstein didn't start on Saturday for the second straight game.
The shortstop and leadoff catalyst is still fighting the effects of a mild concussion suffered while breaking up a double play in Thursday's game against the Pirates.
He received a CAT scan after that game, and Cardinals head trainer Barry Weinberg said X-rays were negative. Weinberg said Eckstein could play when his headaches subsided. They had improved on Saturday, but La Russa still didn't start him.
"He was honest," La Russa said. "He doesn't have any headaches, but he does have a sore spot when it's touched. He worked out and talked to a trainer. It's not smart to push it. Yesterday, he was unavailable. Today, he would be available if we needed him."
Eckstein, among the National League leaders in hits and batting average, didn't know if he will start on Sunday.
"We are not going to make a decision now and just see how the progression is going," Eckstein said. "[We] don't want to sit there and say one thing, and then something else will happen. We will make that decision tomorrow."
Hector Luna started at shortstop for the second straight contest. Luna, batting over .450 in his last 10 games, also batted leadoff, the first time this season he started at the top of the lineup.
Aaron Miles, who had hit first the only two games Eckstein hadn't started, returned to his customary eighth spot.
"I just think it is a better, balanced lineup," La Russa said.
Hawksworth earns start: Blake Hawksworth earned the start for the East Team in the Florida State League All-Star Game on Saturday night. The right-hander, picked in the 28th round of the 2001 draft, is 6-2 with a 2.47 ERA in 13 starts.
Baby Birds: Triple-A Memphis snapped a three-game losing streak on Friday, defeating Omaha, 9-4. Anthony Reyes improved to 4-1, tossing six innings and allowing four runs on seven hits. ... Chris Lambert threw one of his best games of the season, throwing eight innings in a 2-0 win for Double-A Springfield against Tulsa. ... Class A Palm Beach is on its All-Star break. ... Class A Quad Cities defeated Wisconsin, 7-1, behind a seven-inning, 10-strikeout performance from Trey Hearne.
Players of the day: Friday yielded two terrific performances from Lambert and Hearne. Lambert, the Redbirds' No. 1 pick in 2004, had a rough start to 2006, but has rebounded in recent weeks. He is currently 6-5 with a 4.58 ERA after Friday's performance. After Friday night, Hearne is 4-2 with a 2.74 ERA in 18 games and five starts.
Coming up: Fresh off a 13-strikeout outing in his last start, Chris Carpenter (5-3, 2.57) takes the hill against Josh Fogg (4-4, 4.91) in the final game of the series. First pitch is set for 1:15 p.m. CT on Sunday.
Conor Nicholl is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.