Clemens hasn't said one way or the other if he will return next season, but the 43-year-old would not make another start after Saturday unless the best-of-seven NLCS goes the distance back to Game 7 at Busch Stadium. But if the Astros were to win the NLCS before Game 7, Clemens would start in the World Series.
Of course, there's always the possibility the Astros could be eliminated from the playoffs before then. If that happens, Saturday could be it for The Rocket.
Typically, when these two teams tangle, a tense game ensues.
The Cardinals won 11 of 16 regular-season games against Houston in 2005. Counting the playoffs, the Cardinals have lost three of the last four meetings to the Astros at Busch Stadium, but all were by three runs or fewer.
Morris beat Houston, 8-5, on April 24, but lost to the Astros the only other time he faced them on Sept. 27. He pitched well, however, allowing two runs on five hits in six innings in a 3-1 loss in the latter game.
In last year's NLCS, Morris had no record with a 5.40 ERA.
"He's always been tough against us," Houston shortstop Adam Everett said. "He's especially tough on right-handed hitters and doesn't give you much to hit."
Clemens, 4-1 with a 2.51 ERA in nine career regular-season games against the Cardinals, was 1-1 with a 2.63 ERA against them in 2005. The right-hander was 1-1 with a 4.15 ERA in the 2004 NLCS vs. the Cardinals.
On Sunday, Clemens pitched in relief for the first time since 1984, pitching three scoreless innings to get the win as the Astros beat Atlanta in 18 innings to clinch the NLDS. Saturday's start will be Clemens' first appearance since then.
"He's rested and ready to go," Astros manager Phil Garner said.
Jim Molony is a national writer for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.