Perez joined Arsenal in a 17million pounds ($22.7 million) deal from Spain's Deportivo La Coruna ahead of the transfer deadline, as coach Arsene Wenger reinforced his attacking options, according to a report in The Independent on Wednesday.
Germany international Mustafi joined on the same day in a 35million pounds ($46.7 million) deal from Spanish side Valencia, a team Perez scored twice against last season on his way to a 17-goal haul in La Liga.
"He is uncomfortable to play against," Mustafi said. "He's a good striker - he has everything a striker needs."
"He's someone you can play well with. He doesn't just run around and wait for someone to give him a pass to score a goal. He works a lot for the team as well and he creates chances," according to The Independent.
Perez and Mustafi trained with Arsenal on Wednesday as the squad returned from the international break, and could feature in Saturday's home match against Southampton.
"He's in the right place at the right time, as he showed last year in LaLiga. I played there for two years and I know it's not that easy to score many goals in LaLiga, because you have great defenders there as well," Mustafi added.
"I think he's going to help the team a lot."
