Raphael Varane and Raul Albiol could start at centre-half for Real Madrid in their Champions League quarter-final second leg at Galatasaray, with coach Jose Mourinho short of other options.
Pepe, who had been pencilled in to replace the suspended Sergio Ramos, did not take a full part in training at the Ali Sami Yen stadium on Monday, while Ricardo Carvalho was not in the squad that travelled to Istanbul on Sunday.
Mourinho told reporters at Monday's pre-game press conference that Pepe had picked up a problem in Saturday's 5-1 La Liga win against Levante, but said he was sure his squad was deep enough to cope.
"[Pepe] had a muscular problem in the game against Levante and is a doubt," he explained. "We will decide tomorrow.
"If Pepe does not play, Albiol will - and I have the same confidence in the two. We have some very good centre-halves, very experienced, except for Varane. It would be better to have everyone, but [Michael] Essien, Nacho or [Alvaro] Arbeloa can also play there."
Such defensive issues may not matter too much for Madrid, given their commanding 3-0 advantage from last week's first leg.
Although maintaining that "not even a 3-0 guarantees you anything in football", Mourinho said he wanted his team to win the second leg and not just do enough to go through.
"My challenge to the players is not to think about 3-0 but just about a football match," he said.
"They will want to win and play to win. Forget 3-0, forget the aggregate, and just think it is a match that we want to win. If we lose 2-0, I will not go home happy. I want to win the match. Nobody plays to lose, even if you can."
Asked whether an intimidating home atmosphere could help the Turkish side, Mourinho said his players would not be fazed by the crowd.
"In other countries - Italy, Spain, Portugal - if their teams lose heavily away from home, their fans would whistle and boo them," he added.
"In Turkey it is different, so I expect a heated atmosphere, but we like that. The players will enjoy playing in a fantastic stadium, with fans who, although they are against us, will make for a nice atmosphere."
Luka Modric looks sure to start given that Xabi Alonso is banned after picking up a controversial late booking in the first leg.
Arbeloa could replace Essien at right-back with the on-loan Chelsea man a yellow card away from a ban, but Kaka has been left behind in Madrid after picking up an injury against Levante.
That leaves just one selection poser in attack between Gonzalo Higuain and Karim Benzema, both of whom have impressed in recent games.
Fit-again goalkeeper Iker Casillas has made the trip, but is again likely to be on the bench.