The Czech boss has admitted there are problems with his Dutch keeper, and shrugged off any impact that summer signing Mattia Destro's injury might have on his side.
The goalkeeper had publicly blasted his trainer for dropping him in favor of Mauro Goicoechea earlier this week, claiming the decision had not been explained to him at length.
But the 65-year-old told reporters: "I've asked Stekelenburg to be more involved with the team. He lives in isolation and only speaks English, something much of the team cannot do.
"When there is a lack of discipline, there is a lack of team spirit. Rules are forgotten, and every so often, things happen that shouldn't. It is difficult to be the coach of Roma. The squad is not at its best, due to training being affected by weather and illness."
Striker Mattia Destro is the latest injury casualty, after Roma confirmed the 21-year-old underwent surgery on his left knee, with his recovery period expected to be approximately eight weeks.
"I have enough strikers," said Zeman in response to questions regarding the Italy international's status.
Destro has only scored four goals in 16 games following a summer switch from Siena.
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