Although Kershaw was listed as Wednesday's starter, Mattingly waited until Tuesday to commit to the lefty even if the Dodgers are eliminated from the playoff race.
There was consideration of shutting Kershaw down with the ace dealing with right hip pain throughout the month, but Mattingly said nothing since his start on Sept. 23 has shown any reason why he can't go one more time.
"He wouldn't be able to do the things he's doing," Mattingly said, on whether Kershaw has been playing with pain. "He couldn't throw. He couldn't actually go out there and play catch."
Kershaw threw eight shutout innings with 10 strikeouts in his most recent outing and he'll get one last chance to pitch Wednesday unless the Dodgers higher-ups decide they don't want to risk anything happening in a potentially meaningless game.
As for the possible tiebreaker game against the Cardinals if all goes the Dodgers' way, Blanton gets the nod instead of Josh Beckett on short rest.
Beckett, who made a name for himself pitching in big games, has given up just one earned run in four of his seven Dodgers starts, including a game on Sept. 13 against the Cardinals as well as his last start Sunday.
Although Mattingly considered it, he decided using Beckett was asking a lot of the veteran and he felt more than comfortable with Blanton, who threw six shutout innings his last time out.
"Joe has pitched in a World Series," Mattingly said. "It's not like he's never been anywhere and pitched in big games.
"Joe can throw the ball where he wants. He can really get the ball to both sides of the plate with some different angles and some different breaking balls."