The 20-year-old midfielder was recently named as the Gunners' Player of the Month for September.
"He is like the younger brother [in the friendship group with me and Auba]!" Lacazette told Arsenal.com. "We all really have a good relationship, we like to work and to laugh together so it's really good.
"I'm really happy for Matteo [for being named September Player of the Month], he played really well, he helped the team when we needed him, he is really improving each season so we are all really happy with his performances this month.
"We can see that every top midfielder in the world is like this [in terms of demanding the ball and being brave]. They all want to take the ball.
"Matteo has a good ambition, he wants to be one of the best players in his position so every day he is trying to be the best and this month he showed that he can be."