Real Madrid have reportedly not yet decided whether to sign a new centre-back during the January transfer window following David Alaba's injury blow.

Alaba suffered a season-ending ACL injury during the La Liga clash with Villarreal last weekend, while Eder Militao remains on the sidelines with the same problem, which he suffered in August.

Militao will not be back until April at the earliest, leaving Antonio Rudiger and Nacho as the only two fit senior centre-backs at the club.

Real Madrid boss Carlo Ancelotti said last week that it was possible a new centre-back could move to Bernabeu when the January transfer window opens for business.

Transfer expert Fabrizio Romano has claimed that discussions are ongoing over an addition in that area of the field, while it is possible that 21-year-old Rafa Marin could be recalled from a loan spell at Alaves.

"From what I am hearing, Real Madrid are still discussing the possibility of signing a new player in January. It is not guaranteed, but it is a possibility that Madrid will not stay with the same squad," said Romano on his official YouTube channel.

"It's one of the possibilities that they might recall Rafa Marin, but it is not easy. Real Madrid are still speaking internally with Juni Calafat (chief scout), with Florentino Perez (president), with Carlo Ancelotti and other people at the club.

"The original plan was to stay with the same squad, but after Alaba's injury, they are now internally discussing potential January signings."

Nacho started alongside Rudiger in the middle of the defence against Alaves on Thursday, but he was sent off in the 54th minute, which led to Aurelien Tchouameni being pressed into action as a centre-back.

"Tchouameni will get angry for this, but he's amazing as a central defender. He is lucky he can play as midfielder and as defender. He has all the qualities to be a top centre-back," Ancelotti told reporters in his post-match press conference.

Lucas Vazquez scored a 92nd-minute winner against Alaves, with Real Madrid moving back to the top of the La Liga table ahead of Girona.

Raphael Varane has been linked with a return to Real Madrid in January, but it is highly unlikely that Manchester United will allow the ex-France international to leave in the middle of the campaign.

Benfica's Antonio Silva and Sporting Lisbon's Goncalo Inacio are also believed to be admired, although it would be very difficult to sign either in the winter market.

Real Madrid have now entered their winter break, with the capital outfit not back in action until January 3 at home to Mallorca.