Tottenham Hotspur are set to take on Arsenal at the Emirates Stadium on Sunday.
Spurs forward Moura knows Luiz well from their time at PSG together, and they have a good relationship.
Moura could be put up against Luiz, when Tottenham meet Arsenal at the weekend.
And the £23 million (BBC Sport) Spurs forward insists that he will not be taken it lightly on his friend, as he is desperate to help Mauricio Pochettino’s side to victory over their North London rivals.
“I am happy for him because it was a good transfer for him to make,” Moura said.
“I am also happy because he is closer to me now. He can come visit me at my home easier because when he was at Chelsea, he was so far away!
“But on Sunday he will be my opponent, I will work and do the best for my team to get three points. On the pitch (our relationship) is different. It doesn’t matter who the opponent is, I need to do my best and try to win.”
Luiz looks an almost certain starter for Arsenal in the derby match, despite a shaky match against Liverpool last time out.
Luiz was partly responsibility for two of the goals which Arsenal conceded in their 3-1 defeat.
The summer signing will need to be in better form if Arsenal are to get a result against Tottenham, who really need a win.
Spurs were beaten 1-0 by Newcastle United last weekend in what was one of the shock results of the weekend.
And if Tottenham are unable to get three points at the Emirates Stadium on Sunday then the pressure will really build on Pochettino’s side.