"You want to make the decision now but certainly we've got to see how everything goes with Kurt," Whisenhunt said. "Even though he may feel great today, there might be a situation where something could come up."
Warner, who sustained a concussion against the St. Louis Rams on Nov. 22, took all the practice time with the starters last week but sat out Sunday's 20-17 loss at Tennessee because of lingering symptoms. That left Leinart the starter without much preparation.
Warner said he feels much better this week but Whisenhunt is putting off his decision in case there are any late setbacks.
"You've just got to make sure. He could be ready to go Saturday and then something could happen Sunday and certainly once again you would err on the side of caution," Whisenhunt said. "I'm sure in some manner or shape it will be a Sunday decision."
Meanwhile, the Cardinals could be without starting left tackle Mike Gandy, who has not practiced this week because of a pelvis injury. Jeremy Bridges would be Gandy's replacement. If Gandy can't start, it would end a string of 31 consecutive games in which Arizona has had the same starting offensive line.
Tight end Stephen Spach also didn't practice because of a sore knee.