The 65-year-old praised the Italy international after his recent top performances, and insisted that his squad remains a competitive one despite a mixed start to the season.
"De Rossi? [There has been] a difference between the technical and psychological side," the Giallorossi boss said in his pre-match press conference. "He now shows more desire to play.
"However, the hierarchies change every week. This is a competitive squad, in which everyone can play."
Zeman's comments come in the same week that Franco Baldini, Roma's general manager, revealed that the club would be willing to listen to offers for De Rossi, who was the subject of a summer bid of €50 million [£40m] by Manchester City.
|STUNTED BY SPURS|
|8/1||Man City are 8/1 with William Hill to draw 1-1 with Tottenham|
Baldini observed: “If we were to get another offer we would listen again. But we could easily decline again.”
Lazio won both all-Roman league clashes last season, and the two sides sit side-by-side (the Biancocolesti in fifth, Roma in sixth) in the Serie A this season with 11 games already gone.
Sunday's kick-off at the Stadio Olimpico is at 15:00CET.