The 23-year-old has placed himself at the disposal of his coach and will play wherever the team needs him at Euro 2012.
La Furia Roja's chances of defending their title took a hit when it was confirmed that David Villa and Carles Puyol would miss the tournament through injury, but Martinez is optimistic that his ability to play in multiple positions will be useful.
"This year I've played both as an attacking midfielder and a central midfielder, but [Athletic Bilbao coach] Marcelo Bielsa has also utilized me as a defender. I'm growing to be more comfortable in new positions," said Martinez at a press conference.
"Puyol and Villa are both vital players, but thankfully everyone in the squad is prepared to give their all, and whoever plays will be able to perform just as well in the stead of those injured."
Martinez also admitted that losing both the Europa League and Copa del Rey finals took a personal toll on him, but insisted the pain has made him stronger.
"It's true that for four or five days I didn't want to leave my house [after the 3-0 loss to Barcelona], but the chance to win another final in Poland and Ukraine makes me learn from the positive aspects of the losses."
Spain kicks off its Euro 2012 campaign against Italy on Sunday.
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