Celta Vigo striker Iago Aspas has told Real Madrid they must contact his club first if they are interested in signing him in the January transfer window.

"Iago Aspas is very quiet in Celta, I have many years left on my contract, and if they want me first they have to agree with the club," he told Marca (h/t Goal's Harry Sherlock). "After that I cannot do anything."

Aspas was linked with a move to the Santiago Bernabeu in the summer, per El Chiringuito (h/t MailOnline's Max Winters). However, the club opted to re-sign Mariano Diaz from Lyon instead.

Real Madrid have struggled for goals this season following the summer departure of Cristiano Ronaldo for Juventus.

They suffered the longest goal drought in their history earlier in the campaign:

Mariano has managed just one goal in eight appearances and is sidelined with a hamstring injury picked up in the Clasico defeat to Barcelona, per Football Espana.

In contrast, Aspas is enjoying another strong season with Celta. The 31-year-old has eight goals in 11 La Liga outings—only Barcelona's Luis Suarez has scored more in the Spanish top flight this season.

His form saw him nominated for October's Player of the Month award:

Aspas has said he was aware of interest from Real Madrid in the summer before they moved for Mariano, per ESPN FC's Adriana Garcia.

"They didn't contact me directly but it's true that there was an interest," he said. "They signed Mariano to fill the void of a No. 9."

Real Madrid are enduring a tough season in La Liga. They were thrashed 5-0 by fierce rivals Barcelona in El Clasico, sacked manager Julen Lopetegui after only four-and-a-half months in charge and are in sixth place in the table.

Former midfielder Santiago Solari has been placed in temporary charge. However, Real Madrid are under pressure to name a permanent replacement.

According to Spanish FA rules, Solari can only occupy the interim manager's position for 15 days, per Sport (h/t Liam Prenderville at the Mirror).

It remains to be seen if Solari will be given the job on a permanent basis, or whether Real Madrid will turn to a more experienced option. 

Yet Real Madrid are willing to make changes in the January transfer window. The club have €200 million to spend and want to buy a centre-back, midfielder and striker, according to Marca's Jose Felix Diaz.

Aspas is a proven goalscorer in La Liga and would be a good short-term fix if he could be tempted away from Celta. The striker will take on Real Madrid on Sunday in La Liga, where a good performance may reignite Real Madrid's interest.