Real Madrid are now 14 points behind La Liga leaders Barcelona and may well have already conceded the title.
Goals from Luis Suarez, Lionel Messi and Aleix Vidal sealed a comprehensive win for Ernesto Valverde’s men at the Bernabeu, with Dani Carvajal seeing red in the second half.
Zinedine Zidane’s position as Real boss will come under huge scrutiny over the winter break, although the club’s president is ready to splash the cash to get them out of trouble.
Spanish outlet Diario Gol says Perez is prepared to fund a spending spree worth £178m (€200m) in the January transfer window.
Real spent fairly modestly by their standards in the summer, just bringing in youngsters Theo Hernandez and Dani Ceballos.
But the Spanish giants lost some senior players with Pepe, James Rodriguez and Alvaro Morata all moving on.
Real look set to start their January spree with a £26.6m (€30m) move for Athletic Bilbao goalkeeper Kepa Arrizabalaga.
Diario Gol say the deal is all but done for the 23-year-old Spaniard to arrive next month and compete with Keylor Navas for the No 1 spot.
Perez also wants to bolster the defence with Italy defender Leonardo Bonucci on the radar.
Bonucci has apparently asked the Real Madrid supremo to recuse him from his current situation at AC Milan, the club he joined from Juventus in the summer.
A move for the 30-year-old would cost around £44.4m (€50m).
And Perez’s final transfer roll of the dice is for a new Galactico – Mauro Icardi.
He is said to have lost faith in Karim Benzema as Real’s central striker, who had another poor game in El Clasico being replaced after 66 minutes.
And also his former world-record signing Gareth Bale’s injury record is now counting against him.
But Icardi will not come cheap with the last figure for him being mooted at £89m (€100m).
Although given it is mid-season and these clubs may struggle to sign adequate replacements Real may be forced to pay more than they want to bring in the trio.
