The 17-year-old shone in the only game Newcastle United won this season - the Capital One Cup victory over Crystal Palace - registering two assists.
And Armstrong continued his form for the reserves recently, scoring twice in a 4-1 friendly win over Burnley.
Alan Pardew appears reluctant to over-use - and perhaps even initially use - the youngster but, if Emmanuel Riviere is out injured and Papiss Cisse is fit enough to start, he could provide the perfect partner for the Senegal striker.
Much has been made of the 23-year-old Argentine's failure to adapt to the Premier League but Pardew is yet to give him a chance in match action.
Ferreyra's attitude and ability has been questioned based on his form in training but he did score in the same friendly Armstrong did against Burnley recently.
The same can be said for young Perez, who has been given a chance on the pitch - but only for a few minutes as a substitute.
Like Armstrong and Ferreyra, Perez is young and can give Leicester City's defence an unkown quantity to deal with. In a behind-closed-doors friendly last month, the striker scored no less than four goals, with one of them being a fine individual effort.
With so many options up front and so many of Pardew's current starters misfiring, surely one of these three deserves a run out against the Foxes.