Duncan has been on a leave of absence since late August as he tends to his wife, Jeanine, who underwent surgery to remove a brain tumor last month. Manager Tony La Russa invited Duncan to join the club for the last day of the regular season, and he made it down to Houston for the game.
"I'll go out there and we'll see what happens," said Duncan, who preferred to say little about his situation to reporters.
"We'll see how it works out."
La Russa acknowledged he was delighted to see his long-time lieutenant, but also continued to make it clear that Duncan's family is his first priority. Neither man ventured any opinion as to whether Duncan might be around for any additional games the Cardinals might play after Wednesday.
"We've taken his process with the guys who have been around him, and worked the process," La Russa said. "I think Derek [Lilliquist, bullpen coach has] done a good job, but we're doing Dave's work."