CHICAGO -- St. Louis Cardinals right-hander Adam Wainwright is expected to come off the injured list to start Monday at Arizona.

The 41-year-old Wainwright was placed on the 15-day IL on July 5 because of shoulder irritation. The three-time All-Star could throw around 65 pitches against the Diamondbacks.

Wainwright went 11-12 with a 3.71 ERA in 32 starts last year, helping St. Louis win the NL Central. But he is 3-4 with a 7.66 ERA in his 18th major league season.

After a series of cortisone injections and bullpen sessions, Wainwright said there's a "dramatic difference" in his pitches, with more life, bite and late movement. Speaking before Sunday's game at the Chicago Cubs, manager Oliver Marmol said this is the best Wainwright has felt all season.

Wainwright was charged with seven runs, four earned, and seven hits in 3⅓ innings in a 15-2 loss at Miami on July 4 in his last major league start

But he is confident he is ready to return.

"When I finally got healthy and passed some tests and strength tests and the ball started coming out nicely, they said 'Hey, are you ready to pitch because we could use you in the spot?'" Wainwright said. "Dude, I said I'm ready."

"I said I'm not coming back if I'm going through the same problems and things," he added. "I will not come back because it's not fair to the team."