McCarthy, 20, sat out the Republic of Ireland's Carling Nations Cup victory against Wales on Tuesday as he only recently recovered from an ankle injury and Martinez did not want him to be risked. However, his absence led to widespread speculation the Glasgow-born player - who qualifies for Ireland through his grandfather - could yet switch sides ahead of next month's Euro 2012 qualifiers. Martinez insists the injury was genuine and that he does not have an issue with Republic manager Giovanni Trapattoni regarding McCarthy, who was withdrawn after he scored twice in the 4-3 victory against Blackburn. He said: "James has had four games in 12 days. He could not finish the 90 minutes in the last game. "We sent a report to the Republic medical staff and I spoke with Mr Trapattoni. Everything is quite clear. He could not be involved. "He needed to have some treatment and regenerate and just be ready for Saturday. They understood that and know exactly what he has been through. James needs to be 100% to perform and club level and international level." Martinez admits McCarthy faces "a very, very deep" decision about whether to switch to Scotland. However, the Spaniard said the player should not be rushed into making one of the biggest decisions of his fledgling career. McCarthy has made only one senior appearance for the Republic of Ireland and that was in a friendly against Brazil, leaving him free to play for Scotland . Martinez said: "I do not know if it is a decision for him to make now or not. We need to give him plenty of time. We need to respect him. "He wants to help Wigan. For me that is fantastic. It (international football) is something he needs to think about with his family, with his friends. "It is something very, very deep. But I do not think he has focused on that at all, although it is great to have two nations fighting over you. "James is probably the most mature 20-year-old in football. It is a compliment to him. I don't think it is going to affect him. It is going to give him a more arrogant feeling if you want." Meanwhile, defender Gary Caldwell, who was part of the Scotland squad this week, could return wearing a face mask after he missed the Blackburn game with a fractured cheekbone. Caldwell took part in training with Craig Levein's men in Dublin but was not involved in last night's victory against Northern Ireland. Martinez said: "Gary has been involved with Scotland and they felt, as we did, it would have been a big risk for him to play Wednesday. "He trained, used the mask and it worked well. I hope he is fit and available this weekend."
