The 18-year-old keeper is living a dream after receiving a last-minute call-up to replace Oscar Ustari in Nigeria.
"My agent called me, he told me and I couldn't believe him, I thought that he was winding me up. It was an incredible bit of news," Martinez told Radio Belgrano, before describing his arrival in the Nigerian city.
"I threw my gloves and boots into a suitcase and I left. I didn't even bring a toothbrush! I am here to test myself and when you are given these chances, you cannot waste them."
Martinez, just 18 years old and a product of the Independiente youth system before moving to England, received the call after Oscar Ustari suffered a knee injury in training and was ruled out of tonight's friendly. He will sit on the bench for the Seleccion, behind Rojo No. 1 Adrian Gabbarini in a team formed from Under-25 players based in Europe.
The goalkeeper has been training with the senior Arsenal team for just over a month.