Having established a four-point lead over Leipzig at the summit of Group F, Madrid can secure top spot with a game to spare by avoiding defeat against the Bundesliga outfit on Wednesday (AEDT).

However, Madrid's efforts to do so could be hampered by the absences of Modric and Benzema, while in-form midfielder Federico Valverde has joined the duo on the sidelines after suffering a knock in the LaLiga win over Sevilla at the weekend.

All three players are set to feature when the World Cup begins in less than a month's time, but Ancelotti does not feel the tournament is impacting players' thoughts.

"I don't think they think about it. It is better to enter the World Cup well, with continuity," Ancelotti said. "They are small things, and we don't want to risk them at an important moment. It is better to lose Modric and Karim for one day than for a month.

"Injuries exist in football. If you don't want to get injured, stay on the couch. I tell my players that. 

"Nothing can be done. I don't think the players are worried about this. If anyone is afraid of training, I tell them to stay home; there are many good series and movies."

With Madrid also topping LaLiga after winning 10 of its first 11 games, Ancelotti believes the timing of the World Cup may benefit his side amid a manic stretch of fixtures.

"It is a very intense period, with many games, too many," he said. "We are holding it well. 

"We have some problems, which is normal when you play every three days. The World Cup comes at the right time."

Madrid's injury concerns could mean several fringe players get an opportunity to impress in Germany, including Marco Asensio, who recently said he was unhappy with his lack of minutes.

Ancelotti remains pleased with Asensio's application and is committed to discussing his future during the World Cup break.

"The club knows very well what I think, and so does Asensio. Soon there is a long break, and it is time to talk about this issue," Ancelotti said. "Until the first phase is over, I don't think we should talk about this issue.

"What I ask of those who play less is that they be serious, professional and endure the difficult moments.

"That's what Asensio and the rest who play less do. Tomorrow we have casualties and their contribution can increase."