The NLCS will open on Saturday at Busch Stadium (7 p.m. CT on FOX), with Wainwright pitching on seven days' rest.
Earlier in the day on Tuesday there were some questions about whether Wainwright would be the Cardinals' choice in their next game. Concerns about Wainwright's health -- he has been dealing with arm issues on and off this season -- led Matheny to acknowledge that the team was getting Lynn ready in case he needed to go in an NLDS Game 5.
"There's no question Waino has been fighting it," Matheny said. "I've not made that a secret, and neither has he. It's all going to come down to how he feels. The likelihood of him saying he can't go is very slim, but it is a possibility that something might not feel right."
Wainwright, who felt fine during and after his light side session on Monday, never planned on not starting that next game. Asked during Tuesday's postgame celebration if he would be the first to get the ball in the NLCS, Wainwright grinned: "What a question."
Limited concerns about the condition of Wainwright's right arm resurfaced after he labored in his Game 1 outing. Wainwright allowed six runs on 11 hits over 4 1/3 innings, equaling his shortest start of the season. He had particular trouble finding command of his fastball, which allowed the Dodgers to jump on his curveball.
Wainwright didn't suggest arm strength being an issue afterward, but he has dealt with arm issues throughout the season. Wainwright skipped a start in June due to soreness around his right elbow. He later admitted to pitching with a "dead arm" in August before rebounding with a strong September. He jumped at the chance to skip his last regular-season start, noting that he needed the rest.
"He's just been grinding," Matheny said. "And when you've been grinding, there are just days where you can't get it right. He was having trouble that Game 1. He's thrown a lot of innings. He's had a lot of work. But that's what your ace does."
No pitcher in baseball has thrown more innings since the start of the 2013 season than Wainwright, who has logged 508 (including the postseason).
Jenifer Langosch is a reporter for MLB.com. Read her blog, By Gosh, It's Langosch, and follow her on Twitter @LangoschMLB. This story was not subject to the approval of Major League Baseball or its clubs.