Paulista joined from Villarreal in the recent transfer window, offering manager Arsene Wenger another option at the back after having to cope with injuries to the likes of Laurent Koscielny and Mertesacker.
It is a signing that has given World Cup winner Mertesacker a great deal of optimism as Arsenal, sitting fifth in the Premier League, eye silverware in the FA Cup and UEFA Champions League.
"We suffered a lot at times with injuries, but also with results," explained Mertesacker. "We want a very deep squad and we look much better now.
"We have that competition in our team and have an addition with a centre-back now, so I think we have a deep and good squad at the moment.
"He is a talent and I think we will get him to the level he needs because he has that potential.
"From my point of view, it is very promising because we were short at the back, especially in the centre position.
"It was a needed position to get everyone going and keep him on his natural position is very important."
Arsenal meet fierce rivals Tottenham at White Hart Lane on Saturday, with Mauricio Pochettino's side just two points behind them.
