Striker Ferreyra, signed on loan from Shakhtar Donetsk, is yet to make a competitive appearance for the club.
And the 23-year-old is unlikely to get his first taste of Premier League football against Swansea City at the Liberty Stadium today.
Ferreyra, a friend of Argentinian countryman Fabricio Coloccini, was allowed to leave Shakhtar on loan beccause of the conflict in eastern Ukraine.
Newcastle have failed to score in four of their first six league games, and the emerging Perez offers a welcome option off the bench for manager Alan Pardew, whose side have lacked ideas in the final third of the pitch.
Alan Pardew: “Ferreyra has been a bit unfortunate since he arrived, and has had a couple of knocks that have knocked him back.
“He had a reserve game recently with Perez, and they both did well.
“Perez is probably just in front of him at the moment.
“He needs a bit more football and a few more games, but he’s another footballer who needs to adapt to the Premier league.
“It’s a tough league. When you don’t start well, it’s more difficult for these guys to adjust.
“The only message I’ve seen on the training ground that they are trying their damned hardest to show that with a result.”