Javi Martinez hasn't received an explanation from Julen Lopetegui as to why he was omitted from Spain's roster for friendlies against Germany and Argentina.

Martinez played for Spain in the 2010 World Cup along with the 2012 Euro and 2014 World Cup.

When asked by ESPN FC's Raphael Honigstein if he has been contacted by Lopetegui, Martinez said: "No, no, no. He never called me or said nothing about it."

Lopetegui selected a number of players in the squad for the first time, including Chelsea wing-back Marcos Alonso, and Martinez said he hopes to prove to the coach that he is still worthy of being included when the World Cup begins in Russia in June.

"I know it's very difficult to get in the national team," Martinez said. "There are such good players there. It's very difficult.

"Of course, I worked very hard to try to go there. I want to keep working hard. It's true that here, a lot of people asked me -- are surprised about why I'm not going on, but I think I have to work. I don't give up and I keep working to try to reach the goal."