Spain and Croatia are both vying for top spot in Group 3 of League A after winning their matchday one matches against England (3-2 away) and Czech Republic (2-1 away) respectively.
The rigorous physical demands of a four-game UNL window and the travel involved make squad rotation a necessity for all 54 nations and de la Fuente told reporters on Monday that he could be shaking up his matchday squad as soon as Tuesday night, when Spain welcome Croatia to Estadio Ramón Sánchez Pizjuán in Seville.
"Playing four matches at this level within ten days is extremely exhausting," de la Fuente said.
"There are players we want to give a break, We need to refresh the team a little. Not only for this reason, but also because the reserve players deserve it.
"This does not worry me at all. The players who take part will be the most prepared."
One reserve player expected to be called up by de la Fuente is Barcelona's 23-year-old Fermin Lopez, who is desperate for some national team duty after the heartbreak of missing the 2026 FIFA World Cup with a foot fracture.
"It was tough because I think I deserved to be there," Lopez told [a href="https://www.mundodeportivo.com/futbol/fc-barcelona/20260924/1004230881/fermin-valoraba-caminar.html" target="_blank"]Mundo Deportivo[/a] last week upon his selection for Spain's current UNL squad.
Lopez earned a national team recall with an explosive start to the season for Barça, recording four goals and two assists in his first four La Liga appearances of the season.
The El Campillo-born Lopez is especially excited about the potential of representing his country in Seville, with his family - including his beloved grandmother [a href="https://tribuna.com/en/blogs/fermin-lopez-shares-heartwarming-moment-with-his-grandmother/" target="_blank"]who went viral for a lovely embrace[/a] during Barcelona's recent win in Seville - set to attend the match in big numbers.
The chances of Lopez getting significant minutes, if not a start, increased significantly when Luis de la Fuente spoke very warmly of what Lopez brings to the national team setup.
"He's in fantastic form, just like (Dani) Olmo," the 65-year-old said at his pre-match press conference.
"(Lopez) gives us energy, vitality, intensity, a lot of talent, class, and finishing ability. He's a world-class player and fits perfectly with our style of play."