Aside from aiming to collect three valuable points for their respective squads, Cristiano Ronaldo and Aritz Aduriz continue their battle to become LaLiga's active leading scorer off headers.
As of now, the Portuguese superstar has scored 46 goals in seven and a half seasons, whereas the Basque striker's tally stands at 45 goals in four more years than his counterpart.
Moreover, Aduriz needs to find the net twice in order to achieve the 100-goals benchmark in an Athletic Club uniform.
It will not be an easy task considering he has only managed to score a pair in 17 outings against Real Madrid.
Nevertheless, the Spanish international has fared better when facing Keylor Navas, whom he's beaten three times, the most in LaLiga alongside Luis Suarez and Piti.
Meanwhile, Ronaldo will be trying to score his maiden goal at the new Estadio San Mames.
The Madeira native arrives to this crucial match on a hot streak, having scored in his last four LaLiga fixtures versus Betis, Las Palmas, Villarreal and Valencia.
Even if he lacks the statistics, Sergio Ramos shall not be forgotten when discussing heading specialists.The Andalusian has scored an incredible 11 goals thus far this season, all of them except for one coming via his head.
Aware that Ramos has been a force lately on set pieces, Ernesto Valverde has designed a special plan to stop the star centre-back in such situations.