JOIN USArgentina international Higuain, who has been first choice ahead of Benzema under Mourinho, may need an operation that club doctors say would sideline him for around two months.
The injury has prompted speculation in local media that the big-spending La Liga giants could buy another striker in the January transfer window but Mourinho stopped short of making a public plea for reinforcements.
“Signing players is not an issue for me to deal with but I already said at the beginning of the season it would be difficult with only Benzema and Higuain,” Portuguese Mourinho told a news conference.
“If I have to go through the rest of the season only with Benzema it will be much more difficult," he added.
Mourinho said he expected Kaka to return in January after "spectacular" work from the Brazilian in his recovery from a knee operation that has prevented him playing this season.