Westbrook, who strained his right oblique in his Sept. 8 start, threw on flat ground each of the last two days and is scheduled to throw a bullpen session on Wednesday. Westbrook said he would likely need to throw two bullpen sessions before he'd feel comfortable pitching in a game.
"If everything feels great with my side, I feel like I just need to get my arm in shape to start a game," Westbrook said. "The way it's gone, the last couple of days felt great. I think a couple bullpen sessions and I'll be ready to go."
The abbreviated absence is a best-case scenario for Westbrook, who missed approximately six weeks during his two previous oblique injuries. Those strains, though, were on his left side, which absorbs more force in a right-handed pitcher's delivery.
With Westbrook working his way back and Chris Carpenter set to make his season debut on Friday, the Cardinals are soon to have a plethora of starting pitching options. Joe Kelly has already been pushed to the bullpen, and Lance Lynn could eventually follow.
Though the Cardinals have laid out tentative pitching plans through the end of the season, the club has not announced how the rotation will set up beyond Saturday.