Karim Benzema has emerged as a severe doubt for Real Madrid's Champions League last-16 first leg against Schalke 04 on Wednesday.

The Frenchman was expected to start in a front three alongside Cristiano Ronaldo and Gareth Bale for the European encounter in Germany.

However, according to reports in the Spanish press, Benzema pulled out of a training session on Tuesday with a bout of flu and his condition has not improved in the hours leading up to the match.

With James Rodriguez also on the sidelines, Isco could be moved into a centre-forward position should Benzema fail to recover from the illness in time.

Last season, Los Blancos beat Schalke 6-1 on their own patch at this stage of the competition.