ST. LOUIS -- Right-hander John Smoltz reported big improvement in his right shoulder Sunday, and he expects to throw a side session this week before starting Sept. 20 against the Cubs.

Smoltz, who will miss his scheduled start on Monday because of tendinitis and inflammation in his right shoulder, said Saturday he probably wouldn't throw much before taking the mound against the Cubs on ESPN.

But after having much more range of motion than he expected on Sunday, he plans to play catch on Monday or Tuesday and hopes to throw a side session no later than Wednesday.

"My routine in situations like this is two, three, four days, and I will be back out playing catch and throwing," Smoltz said. "I can pitch through it. Tendinitis, in most cases, you warm up and get through the rough point and you don't miss a beat. But you know that it will take more and more of that and get harder and harder to get loose.

"I could definitely feel it right away. But I've pitched through a ton of that. It's not something you can't pitch through, but if given the opportunity to take a break, you're just way ahead of the game."

The future Hall of Famer is 1-1 with a 3.27 ERA in four starts since joining the Cardinals.

Smoltz repeatedly has downplayed the setback and said he would have been fine to start if it was a playoff game. But with the Cardinals holding a healthy lead in the National League Central, the righty decided he and the team would be better off if he let the inflammation calm down.

"No use going through that when you don't have to," Smoltz said.

The plan for Smoltz in the playoffs hasn't been decided, but it appears he will finish the rest of the regular season as a starter. He could remain in the rotation for the postseason as the team's fourth starter, or he could move to a late-innings setup role for closer Ryan Franklin.