Atletico Madrid midfielder Saul Niguez has vowed to "make things difficult" for Spain boss Julen Lopetegui when it comes to selecting his starting XI for the 2018 World Cup.

Saul will enter the tournament off the back of another strong season for Atletico, but the 23-year-old is widely expected to be a squad member for La Roja in Russia rather than a starter.

The midfielder, however, will be looking to impress his national team manager in the country's upcoming friendlies with Switzerland and Tunisia ahead of the tournament.

"There are two friendlies and several training sessions for me to convince the coach and make things difficult for him," Saul told Radio Marca.

"Julen has the power to decide, but I'm going to contribute and try to help Spain get that second star on our shirts, because nothing would make me more excited than that."

Versatile midfielder Saul is yet to score in his nine appearances for Spain.