"He did okay," said Simon Grayson of Nunez, who has won 21 caps for his country. "We'll keep him here for another week as sometimes you only get two or three days to have a look.
"We got him a game last week and might try and get him a game for the reserves next Wednesday.
"He's a busy player who plays off the strikers. He's got a lot of qualities, as you don't have the experience he has if not. But we have to see if he can make us a better team."